Explained | Nukes in space: What have Russia and the United States said?

Moscow/Washington: Unidentified sources in the United States say Russia is developing a space-based anti-satellite nuclear weapon but President Vladimir Putin said he opposes nuclear weapons in space and Moscow has flatly denied the US assertions.

Who has said what and what would such a weapon mean?

WHAT DOES THE US SAY?

The United States believes Russia is developing a space-based anti-satellite nuclear weapon whose detonation could disrupt everything from military communications to phone-based ride services, a source familiar with the matter said on Tuesday.

The source, who spoke on condition of anonymity, said it was his understanding the system would involve a nuclear explosive device placed into orbit.

Reports about possible Russian development emerged after the Republican chair of the US House of Representatives intelligence committee on February 14 issued a cryptic statement warning of a "serious national security threat."

The clearest public sign Washington thinks Moscow is working on a space-based anti-satellite nuclear weapon was a White House spokesperson's comment on Thursday that the United States believes the system being developed would violate the Outer Space Treaty.

The 1967 treaty bars signatories – including Russia and the United States – from placing "in orbit around the earth any objects carrying nuclear weapons or any other kinds of weapons of mass destruction."

The New York Times reported on Saturday, without citing sources, that in recent weeks a warning has circulated from America's spy agencies that Russia may be planning a new secret military satellite launch and that the key question was whether it would use it to put an actual nuclear weapon into space.

Bloomberg on Tuesday reported Russia could deploy a nuclear weapon or a mock warhead into space as early as this year. It also cited unnamed sources as saying the United States believes Russia does not plan to detonate a device but that there was risk of an accidental explosion, disabling scores of satellites.

The White House and the Office of the Director of Intelligence declined comment on the Bloomberg report.

WHAT DID MOSCOW SAY?

"Our position is clear and transparent: We have always been categorically against and are now against the deployment of nuclear weapons in space," Putin told Sergei Shoigu, his defence minister at a televised meeting in the Kremlin.

"We urge not only compliance with all agreements that exist in this area, but also offered to strengthen this joint work many times," Putin said.

He added that Russia's activities in space did not differ from those of other countries, including the United States.

Commenting on the weapons in space allegations, Shoigu said there were no plans of the kind outlined by the unidentified sources in the United States.

"Firstly, there are no such projects - nuclear weapons in space. Secondly, the United States knows that this does not exist," Shoigu told Putin.

He accused the White House of trying to scare US lawmakers into allocating more funds for Ukraine as part of Washington's plan to inflict what he said was a strategic defeat on Russia.

He said the second reason for the leaked information about the alleged Russian weapon was to encourage Russia to engage in a dialogue about strategic stability.

Russia's full-scale invasion of Ukraine in February 2022 has led to the most serious confrontation between Moscow and the West since the 1962 Cuban missile crisis, and the post-Cold War arms control architecture has crumbled.

Putin said Russia had never been against discussions about strategic stability.

WHAT WOULD NUKES IN SPACE MEAN?

The exact nature of the alleged weapon is unclear. Both Russia and the United States have vast nuclear arsenals and advanced space programmmes.

Threatening satellites could cause all sorts of mischief - undermining communications, surveillance, intelligence and command and control around the world, including in the nuclear sphere.

But it is unclear why Russia would need to use nuclear weapons to destroy a satellite, when conventional weapons could do the job, or whether the United States has been developing nuclear capabilities in space.

If Russia did develop such a weapon, then the United States would be forced to do something similar and perhaps China too - and so there would be a risk of some sort of nuclear space race.

Russia and the United States together hold about 90 per cent of the world's nuclear weapons, and both have advanced military satellites orbiting the Earth.

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.

The United States casts Russia and China as its biggest nation-state competitors and says both 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.