Russia wants to put a nuclear weapon into space, US intelligence indicates, in what was described as a “serious national security threat”.

Joe Biden was urged on Wednesday night to declassify US intelligence on the military operation, which has been shared with every member of US Congress.

The weapons system could be used to target Western satellites in space, potentially knocking out communications and military targeting systems.

The US president is understood to have been tracking the threat, described as a “grave” but not “immediate”, for some weeks, according to White House sources.

Republican Mike Turner, the head of the House intelligence committee, revealed the existence of the intelligence in a public statement calling on Mr Biden to share it with the public.

Sources told ABC News that the intelligence had to do with Moscow seeking to put a nuclear weapon in space. The weapon would not be used against targets on the ground, the sources said, but described the intelligence as “very concerning and very sensitive”.

On Wednesday night, US officials told the New York Times the nuclear capability had not been launched and was still in development.

It comes amid growing fears that Russia’s war in Ukraine has escalated the potential for a clash between Moscow and Nato.

White House officials said on Wednesday that they assessed the threat to be “serious” but believed there were ways to “contain” it without triggering mass panic.

Dr Malcolm Davis, a senior analyst at the Australian Strategic Policy Institute, said: “If Russia has, in fact, deployed, nuclear weapons in orbit, that would be a deliberate and direct violation of the 1967 outer space treaty by Moscow.

“The outer space treaty is a cornerstone of space stability, and this would be a grave setback for international arms control,” he told The Telegraph.

Jake Sullivan, Mr Biden’s national security adviser, is due to brief the so-called “Gang of Eight”, the top leaders in Congress, on the intelligence on Thursday.

Mr Sullivan said he had taken the “highly unusual” step of offering himself up along with the country’s top “intelligence and defence professionals”.

Asked whether the public had nothing to worry about, Mr Sullivan said: “That question is impossible to answer with a straight yes”.

“Americans understand that there are a range of threats and challenges in the world that we’re dealing with every single day,” he said.

Mr Sullivan’s remarks came after senior figures in Congress who have been granted access to the intelligence voiced alarm and demanded the information be released to the public.

Mr Turner said the urgent matter was in “regard to a destabilising foreign military capability”.

He took the rare step of making the information available to every member of Congress in the secure rooms in the Capitol, where the country’s most sensitive information can be viewed.

“I am requesting that President Biden declassify all information relating to this threat so that Congress, the administration, and our allies can openly discuss the actions necessary to respond to this threat,” he said.

His Democratic counterpart on the committee, Jim Himes, said Mr Turner was “right to highlight the issue”, but urged calm. “People should not panic – that is unequivocal,” Mr Himes said.

He added: “I don’t want people thinking that martians are landing or that your Wednesday is going to be ruined. But it is something that the Congress and the administration does need to address in the medium to long run.”

Mike Johnson, the House Speaker, echoed the comments, saying there was “no need for public alarm”. “Steady hands are at the wheel, we’re working on it,” he added.

The letter from the House intelligence committee to all members of Congress warned the panel “has identified an urgent matter with regard to a destabilising foreign military capability that should be known by all congressional policymakers”.

The White House was surprised by the move. Mr Sullivan said: “I am confident that President Biden, in the decisions that he has taken, is going to ensure the security of the American people going forward.”

He added: “I’ll just say that I personally reached out to the Gang of Eight. It is highly unusual, in fact, for the national security adviser to do that.”

Mr Sullivan went on to stress that the Biden administration had “gone further and in more creative, more strategic ways, dealt with the declassification of intelligence in the national interest of the United States than any administration in history”.

Last week, the Danish defence minister Troels Lund Poulsen warned the rapidity of the Kremlin’s military production meant it could attack a Nato country “within a three-to-five-year period”.

“That was not Nato’s assessment in 2023. This is new knowledge that is coming to the fore now,” he stressed.

Such an attack would test Article Five of the military alliance, which holds that an attack on one member represents an attack on all and should trigger a collective response.

Kremlin dismisses U.S. warning about Russian nuclear capability in space

Kremlin spokesman Dmitry Peskov attends a meeting between Russian President Vladimir Putin and Iranian President Ebrahim Raisi in Moscow.

Russia on Thursday dismissed a warning by the United States about new Russian nuclear capabilities in space, calling it a "malicious fabrication" and a trick by the White House aimed at getting U.S. lawmakers to approve more money to counter Moscow.

The United States has told Congress and allies in Europe about new intelligence related to Russian nuclear capabilities that could pose an international threat, a source briefed on the matter told Reuters on Wednesday.

The new capabilities, related to Russian attempts to develop a space-based weapon, do not pose an urgent threat to the United States, the source said.

Kremlin spokesman Dmitry Peskov said he would not comment on the substance of the reports until the details were unveiled by the White House. But he said Washington's warning was clearly an attempt to get Congress to approve more money.

"It is obvious that the White House is trying, by hook or by crook, to encourage Congress to vote on a bill to allocate money, this is obvious," Kremlin spokesman Dmitry Peskov was quoted as saying by state news agency TASS.

"We'll see what tricks the White House will use," Peskov said.

Deputy Foreign Minister Sergei Ryabkov, Moscow's point man on arms control, accused the United States of "malicious fabrication", TASS reported.

Russia's invasion of Ukraine - something Moscow calls a special military operation - has triggered the biggest confrontation between the West and Russia since the 1962 Cuban Missile Crisis. Both Moscow and Washington have warned of the risk of a conflict between NATO and Russia.

Russia and the United States are by the biggest nuclear powers: together their arsenals hold about 90% of the world's nuclear weapons, and both have advanced military satellites orbiting the earth.

SPACE NUKES?

The United States casts Russia and China as its biggest nation-state competitors, and Washington says both Moscow and Beijing are developing a range of new weapons systems, including nuclear, cyber and space capabilities.

Russia says the post-Cold War dominance of the United States is crumbling and that Washington has for years sown chaos across the planet while ignoring the interests of other powers. Moscow says the United States too is developing a host of new weapons.

In the early years of the Cold War, after Russia leaped ahead in the space race and both sides developed intercontinental ballistic missiles, the West proposed a treaty to outlaw nuclear weapons in space.

The eventual result was the 1967 Outer Space Treaty which bans putting any weapons of mass destruction into orbit or in outer space.

In recent years, disagreements between Moscow and Washington have eroded the framework of arms control treaties that sought to reduce the risk of nuclear war between them.

The New York Times and ABC News reported earlier that the new U.S. intelligence was related to Russian attempts to develop a space-based anti-satellite nuclear weapon.

It was not immediately clear why Russia would need a nuclear weapon to destroy a satellite.