Sometime on Oct. 21 of last year, high above the Arctic Circle, a lone missile shot skyward from a Russian island.

The missile flew northeast and then banked and began flying in loops for hours over the barren, frozen landscape.

According to Russian and Western sources, the new weapon, known in Russian as Burevestnik and by NATO as Skyfall, was powered by a small nuclear reactor. Few other details were forthcoming.

Now, two MIT researchers have published an analysis that sheds fresh light on how the nuclear-powered missile actually worked. If they are correct, the October flight test marks the first time a nuclear-powered aircraft has ever flown. It would also suggest the opening of an extraordinarily dangerous new chapter in the 21st century's simmering arms race.

"This is something that is possible, but wildly expensive and very dangerous," said Jake Hecla, a professor at the Massachusetts Institute of Technology with a dual appointment in both aerospace and nuclear science and engineering, who led the new analysis along with co-author R. Scott Kemp.

Their modeling shows a reactor design that spews radiation as it flies, putting anyone living or working near the test site for the missile at "enormous risk, potentially."

The dream of nuclear flight

Since the 1950s, both the U.S. and the then-Soviet Union contemplated building nuclear-powered aircraft. Such weapons had the potential to give both sides an advantage in the Cold War because they would have nearly unlimited range. That could allow them to loiter near a target awaiting an attack order almost indefinitely, or they could attack from an unpredictable direction, making it harder to defend against.

In 1955, the U.S. Air Force put a small nuclear reactor inside a Convair B-36 strategic bomber to test whether it would expose the crew to excessive amounts of radiation in flight. The reactor was never hooked up to the plane's engines, but it did show that a nuclear reactor could fly. In 1961, the Soviet Union conducted similar experiments aboard a modified Tupolev TU-95 bomber.

Safety concerns left those concepts grounded, but the U.S. also worked on a series of nuclear reactors to power missiles. Known collectively as Project Pluto, the idea was to build a supersonic low-altitude cruise missile that could deliver a nuclear weapon to any point on Earth. The tests culminated in 1964, with the ground test of a reactor mounted on a railroad car in Nevada that could run for five minutes, producing 513 megawatts — equivalent to more than 35,000 pounds of thrust.

When news of the new Russian cruise missile first emerged, many onlookers assumed it would be a variant of the Project Pluto engine, but Hecla was skeptical. Project Pluto's design, known as a ramjet, required air to move through it very quickly and could only operate at supersonic speeds.

"There are a number of reasons we have to suspect that a nuclear ramjet is infeasible for Burevestnik," he said. In particular, the shape of the weapon looks much like a conventional subsonic cruise missile.

"You can see very obviously that it is a subsonic system, and ramjets are not very efficient at subsonic speeds," he said.

A new kind of reactor

To try and figure out how the weapon was powered, Hecla first used a handful of videos posted by Russian media to determine its dimensions. He identified objects of known size in the factory where the videos were filmed — things like a utility desk or a fire extinguisher. Through many hours of repeated measurements, he was eventually able to build a three-dimensional model of the missile.

Based on the measurements, he concluded that Burevestnik is larger than even the largest Russian cruise missiles, but it is by no means enormous. Aerodynamic modeling showed it would need to travel around Mach .75 or about 575 miles per hour to stay airborne. That speed is similar to a commercial aircraft, like the Airbus A320.

Hecla now knew roughly how big the reactor could be and how much thrust it needed to produce to make Burevestnik fly. Based on that data, and his knowledge of nuclear engineering, he was then able to model the type of reactor that might be powering the missile.

His conclusion: "It's almost certain that the system uses a direct-cycle air-breathing nuclear propulsion system, most likely driving a turbojet," he told NPR.

A direct-cycle system means that the reactor runs by pushing air from the atmosphere directly through the nuclear fuel. A compressor forces the air through tiny straw-like channels in the reactor core, where nuclear reactions cause the air to heat and expand out the back of the engine. Such a system is radically different from most nuclear reactors, which use an "indirect" closed loop. Those sealed systems are filled with water or another coolant and transfer heat out of the reactor while limiting radiation exposure.

Hecla said he can't completely rule out that some sort of indirect loop is used in the missile, but given the complexity and extra weight involved with building such an indirect system, he finds it far more likely that Burevestnik is heating air by sucking it right through the reactor core.

And that's a big problem. "The direct cycle is very likely to result in a large quantity of radioactive material in the exhaust," Hecla said. Air itself is irradiated as it passes through the engine, and fission decay products from the nuclear fuel also diffuse into the straw-like cavities and are shot out the back.

Hecla said his calculations show that a direct-cycle system would produce large quantities of radioactive isotopes of argon, krypton and carbon. He admits the reactor could release still more radioactivity if the core starts to corrode during hours of flight.

"Heated, compressed atmospheric air is very good at eroding engine components," Hecla noted. There's no reason to think this new nuclear reactor would be different.

"A terrible idea" 

If Hecla is correct, then Burevestnik is the first aircraft ever built and flown using nuclear power. It's also incredibly problematic, said Jeffrey Lewis, a scholar at Middlebury College who specializes in studying rockets and missiles and was not affiliated with the MIT study.

"This thing is an environmental nightmare," Lewis said. In addition, the reactor poses a huge risk to members of the military who might be required to handle it. "Just the question of how you safely load one of these things is, I think, really pretty challenging," he said.

In 2019, an accident off the Russian coast killed several Russian nuclear personnel. Shortly thereafter, a spike in radioactivity was detected nearby. It's now widely believed the accident was the result of a Russian team attempting to recover a prototype Burevestnik reactor. Hecla said it's possible that the reactor restarted as it was being hauled from the bottom of the sea, sparking an explosion.

Given all the problems, both real and potential, associated with Burevestnik, Hecla questions why the Russians developed it at all. He notes that although its range is likely significantly longer than that of a conventional cruise missile, that doesn't mean it's particularly hard to intercept.

"It's not a game-changing idea by any stretch of the imagination," he said. "We are able to routinely shoot down cruise missiles today, and there is no reason to think this will be particularly more difficult to do."

Moreover, Russia has said that Burevestnik will only be used with a nuclear weapon as its warhead. A conventional warhead would likely be heavier, Lewis noted, and the reactor would still end up spreading lethal radiation over a significant area where the missile strikes. Given all that, "I can't see the Russians wasting one to deliver a few hundred pounds of explosives," he said.

Put it all together, and the weapon appears to be "kind of useless," Lewis said.

Hecla suspects that Burevestnik's development may be advancing for one of two reasons. First, he said, it's possible that somebody within Russia's nuclear industry has simply caught President Vladimir Putin's ear and convinced him to invest in the program. Second, he speculates, it might be possible that the reactor in Burevestnik is just a stepping stone to developing nuclear-powered surveillance drones or space-based nuclear systems that could be useful for other missions.

Lewis agrees that the nuclear-powered missile probably isn't very useful as a weapon. But Hecla's paper at least shows it is technically feasible that the Russians have developed it: "It might be a bad idea, it's almost certainly a terrible idea," he said. "But it's not an impossible idea."

At least 37 people have been killed after Russia attacked a Ukrainian ammunition depot with a drone as strikes on Kyiv continued for a third day.

Fire erupted at the depot, in the village of Myla in Kyiv's Bucha district, as more than 200 people evacuated their homes and 50 residential buildings were destroyed.

Ukraine's President, Volodymyr Zelensky, said the warehouse had been struck 'followed by a detonation'. 

He also announced a probe had been launched into the matter. It is forbidden to store ammunition close to civilian homes in Ukraine. 

Air raid sirens sounded 11 times in 24 hours as further drone and missile attacks were expected.

One home in Bucha was destroyed and seven others damaged as the depot fire spread to residential areas.

'Those who allowed this to happen must be held accountable for their decisions,' Zelenskyy said.

A care home for elderly people and people with disabilities had been damaged, and an evacuation is ongoing, he added. 

Prime Minister Serhii Korteskyi did not share information about the incident and instead referenced a previous attack on another ammunition depot in July. 

The warehouse, located in the Kyiv suburb of Vyshneve, was targeted in an attack that killed 22, triggering large detonations and fires that tore through homes. 

'Unfortunately, we can already see that the terrible tragedy in Vyshneve did not become a lesson,' Koretskyi said. 

'In the fifth year of a full-scale invasion, making the same mistakes is criminal negligence. 

'And all those guilty, without exception, must be severely punished so that such situations do not happen again.'

Meanwhile, the Kremlin confirmed it had struck the warehouse in Myia, claiming it stored launch boosters and long-range drones. 

It also said it had attacked Mykolaiv, Izmail, and a logistics centre and warehouse facilities storing parts for Ukraine's Flamingo cruise missiles in the Kyiv region

Zelenskyy later announced that two officials from state-owned companies, including Ukraine's largest arms producer, Ukroboronprom, had illegally allowed the storage of weapons on the site in Vyshneve and would be held accountable.

Kyiv's regional military administration chief Timur Tkachenko expressed his 'sincere condolences to the families and loved ones of those killed' in the latest attack on Myla

The attack on the Ukrainian village comes as Russia enters its third successive day of trying to paralyse Kyiv.

Russian strikes on the southern Kherson region Saturday killed two people and wounded 27 more, Oleksandr Prokudin, head of the region administration, said.

Homes and apartment blocks were damaged in the strike, and one child was among the injured, he added. 

Earlier in the week, Prokudin said that Russia has intensified attacks on critical infrastructure in the region, which is about 70 per cent under Russian control. 

He also urged tens of thousands of residents to move to safer regions because of the possibility of prolonged power and heating outages this winter.

Russia has significantly increased its use of jet-powered drones, and their numbers will keep growing as Moscow sees their effectiveness, said Pavlo Palisa, the deputy head of Ukraine's presidential office.

'Means of attack always outpace means of defence. We will certainly need to adapt. It will take time,' Palisa said. 

He said interceptor drones currently available to Ukraine, which could theoretically intercept jet-powered drones, have not yet demonstrated the expected effectiveness, though Ukraine is working on solutions.

Meanwhile, Ukraine has stepped up its long-range attacks on Russian military industries and energy facilities in recent months, using locally made drones, aiming to cut Moscow's revenue for its invasion and make Russians feel the consequences.

In his evening statement to the nation Friday, Zelenskyy said Kyiv hoped to increase its long-range strikes on Russia to reach 1000 drone launches every day.

'Right now, we average over 300 of our long-range strikes,' Zelenskyy said, his preferred term for Kyiv's long-range attacks that have also lately targeted Russian large-scale online retailers. 

'There must be more. We have a very specific goal, and we will achieve it.'

Moscow's forces destroyed 313 Ukrainian drones overnight, Russia's Ministry of Defence said on Saturday.

Ukrainian drone attacks wounded 11 people in Russia's Rostov region, Governor Yuri Slyusar said.

Writing on social media, he said that nine people were hospitalised, including four children.

Putin's latest attacks came the week after CIA director John Ratcliffe made a secret trip to Moscow, which prompted speculation the Russian leader may have threatened the Baltic states.

US media reported Mr Ratcliffe warned Russia against attacking Nato members – particularly Estonia, Latvia and Lithuania – amid warnings Moscow could try to test the alliance.

But experts said there was no sign of the large-scale military build-up that preceded the invasion of Ukraine in February 2022.

Overnight Ukraine targeted Russia's Rostov region, hitting a warehouse owned by retail chain DNS and Amazon-style online marketplace Ozon with drones.

Residents said there were dozens of explosions as the DNS depot was engulfed in flames while a shipbuilding plant was also hit.

Ukrainian strikes have crippled the region's ports and prevented agricultural exports, prompting a state of emergency as farmers complained of an unprecedented collapse in wheat prices.

Drones intercepted by Russia damaged tower blocks in Aksay, Rostov-on-Don, where seven people were injured.

And in the occupied Kherson region, Ukrainian strikes on power plants caused widespread blackouts.

John Ratcliffe’s meeting this week with a Russian intelligence chief was aimed at pushing the Kremlin to pursue a peace deal with Ukraine.

news analysis

There is little sign that public exhaustion, economic headwinds or increased Ukrainian strikes are changing the Russian leader’s view that he will eventually achieve victory.

CIA Director John Ratcliffe’s secret trip to Moscow involved telling one of Vladimir Putin’s top officials that Russia needs to end the war in Ukraine before its economic situation worsens, according to a report.

Ratcliffe met with Aleksandr Bortnikov, director of Russia’s Federal Security Service (FSB), to deliver a warning that Russia’s military and economic situation will only get worse unless it negotiates a peace deal with Ukraine to end the four-and-a-half-year conflict, sources told The New York Times.

CIA analysts fear that Putin’s advisers are not providing the Russian leader with frank updates about how the invasion is going, as Ukraine continues to bombard the country with wave after wave of drone attacks.

Some officials believe that having Ratcliffe deliver the bleak message himself would lead the Russian president to take the warning more seriously than if it were delivered through normal diplomatic channels, according to the Times.

For years, Trump and his advisers believed that a Russian victory over Ukraine was inevitable. The Trump administration has also scaled back the amount of military aid it has sent to Ukraine as the war drags on.

However, Kyiv has changed tactics, fighting back with long-range drone strikes targeting Russia’s economy and fuel supplies that have put Moscow on the back foot. This includes repeated attacks on major Russian oil refineries, which are used to fund Moscow’s war efforts.

Ukraine has also targeted warehouses and facilities belonging to Wildberries, Russia’s largest online retailer, which is often described as the country’s equivalent of Amazon.

Ratcliffe’s visit to Moscow this week came after the CIA director suggested that Ukraine was getting the upper hand in the conflict because of its use of drones. Speaking to the Times in June, Ratcliffe said that the life expectancy of a Russian soldier on the front line in Ukraine was less than 35 minutes.

“Much of the reason is technology and how drones have become super-efficient, low-cost killing machines,” Ratcliffe said.

Ratcliffe also noted that Russia had gained only about 1 percent of Ukrainian territory since he became CIA director 18 months ago, while simultaneously suffering major losses on the battlefield.

It was previously reported that Ratcliffe’s trip on Tuesday was to warn Russia not to launch an unprovoked attack on NATO countries. It is feared that Putin could lash out and test the resolve of the military alliance by launching an attack ranging from a cyberattack to an incursion into a neighboring country.

Any scenario in which Putin attacks a member of the military alliance could have devastating consequences around the world. Under NATO’s Article 5, an attack against one NATO country is considered an attack against all 32 allied members, including the U.S.

On Thursday, The Washington Post also reported that the Kremlin considers the U.S. significantly weaker because of the Iran war and dwindling weapons stockpiles. It is feared that Putin could use this as an excuse to provoke U.S. allies in Europe, believing that any response would be severely hindered.

A source told the Post that Ratcliffe’s trip to Moscow was “less about Putin being in a corner” and more because Russia believes “we are depleted and can’t intervene.”

Trump, who has downplayed the significance of Ratcliffe’s visit to Moscow, said he is not concerned that Putin will attack a NATO country.

“There is no problem,” Trump told Axios on Thursday. “Ratcliffe sees his Russian counterpart once every six months or once every year. They have a very good relationship. There was no message, and there was nothing unusual.”

The Daily Beast has contacted the White House and the CIA for comment.

Russia has warned it could strike British military targets over the UK’s support for Ukraine.

Russia’s foreign ministry spokesperson told the UK to back off on what she called London’s hostile stance on the war, which she said risked taking the conflict to an entirely new level.

Maria Zakharova told the same Moscow news briefing earlier that Britain and France were “playing with fire” by supplying sensitive missile technology to Ukraine.

But the Ministry of Defence has hit back, saying Russia “should be in no doubt about the resolve of this government to stand against Russian aggression, in Ukraine and against the UK and our allies.”

Britain announced on Monday it would allow Kyiv access to classified technology to start its own production of Storm Shadow long-range cruise missiles, capable of carrying out strikes deep within Russia. France has already given its assent to licence the technology for the European missile.

That decision has drawn strong condemnation from Russia, with president Vladimir Putin’s spokesperson Dmitry Peskov saying it would add “fuel to the fire” of the conflict.

But Andy Burnham told reporters in Kyiv during a visit earlier this week: “Who started the fire? That’s the question, isn’t it?”

Russian intervention comes as tensions between the Kremlin and Downing Street continue to escalate, a week after Russia’s embassy in the UK said reports that Ukrainian forces had used unmanned aircraft manufactured by two UK companies “confirm that London is deliberately opting for an escalation of the Ukraine crisis”.

But former ministers have said Mr Burnham must not flinch in the face of the threats.

Former foreign secretary Sir Malcolm Rifkind told The Independent: “This is probably usual sabre-rattling from Russia.

“It is not impossible they might try a significant cyber attack or something military to appear macho. If they do, they should remember that the UK has offensive cyber capability and could use it!”

Former defence secretary Grant Shapps said: “The real Russian threat to this country is not a missile over Hertfordshire – it is sabotage, cyberattacks and hybrid operations against our defence industry, our undersea cables and our critical national infrastructure, deniably and by proxy. That is where ministers must harden our defences now, not after the fact.

“The answer to intimidation has never been to back away from it. If London flinched every time Moscow rattled the sabre, the sabre would simply be rattled more often, and next time over Poland or the Baltics. We should say plainly to the Kremlin: your threats will not divide us from our allies, they will not slow a single delivery to Kyiv, and the fastest way to end the risk you claim to fear is to withdraw your forces from Ukraine."

Moscow accused Britain of “seeking to contain Russia and inflict maximum damage on it by proxy” and warned that the deeper its involvement becomes, “the higher the price it will pay”.

“London’s actions will inevitably carry consequences for which it will have to answer,” it said.

But Mr Burnham hit back, saying Britain would not be deterred by the threats. The prime minister visited Kyiv this week in his first trip abroad since entering Downing Street.

While in the capital, the UK reaffirmed its “unwavering” commitment to Ukraine, which in turn provided what officials described as a “goldmine” of combat data to enhance British security.

During his visit, the prime minister urged Ukraine’s allies to send more interceptor missiles to Kyiv as Ukraine struggles under continued Russian bombardment.

He co-chaired his first coalition of the willing meeting, where he said the group was doing “everything we can” to “dig into our own stocks and help others dig into their stocks”.

Whilst he was visiting the country, Kremlin adviser Andrei Fedorov warned that British factories manufacturing drones for Ukraine could face targeting by “unknown sources”.

The former deputy foreign minister for Russia stated he could not “100 per cent exclude” the possibility of “semi-military” operations directed at Britain.

Mr Fedorov told BBC Newsnight that “sooner or later, there might be not only verbal, but maybe some visible reaction from Russia towards the UK”.

Asked to elaborate, he said: “There are different discussions about how it should look – it might be a so-called technical reaction, maybe some hacker attack from an unknown source, not from the official level, of course.

“There might be different political steps, and I cannot exclude 100 per cent that there might be some semi-military, for example.”

Pressed to define “semi-military”, he said: “For example, something might happen with enterprises, with the factories which are producing drones for Ukraine, etc etc.”

Asked whether this meant British factories in Britain being attacked militarily by Russia, the adviser said: “They could be attacked, not by Russia, but by ... unknown sources.”

A Ministry of Defence spokesperson said: “Britain stands shoulder to shoulder with Ukraine and we are committed to providing the equipment Ukraine needs to defend itself against Putin’s illegal invasion.

“Russia should be in no doubt about the resolve of this government to stand against Russian aggression, in Ukraine and against the UK and our allies."