Ben Tobias is a news correspondent for the British Broadcasting Corporation.

A view of the ISSImage source, Reuters
Image caption, The ISS has orbited Earth since 1998

Russia plans to build its own space station after leaving the International Space Station.

Since 1998, the US and Russia have collaborated on the International Space Station.

Relations have soured since Russia invaded Ukraine and Russia threatened to quit the project.

No official notice of Russia's intention to leave the programme has been received.

Since 1998, the International Space Station has been used to conduct thousands of scientific experiments.

The US wants to extend it for six more years with the approval of all partners.

At a meeting with Russia's President Vladimir Putin, Mr Borisov said that the project would be stopped after four years.

Mr Borisov said that the new station would be his agency's top priority.

Mr Putin said good things.

It's not clear what the decision means for the future of the International Space Station, and the US space agency doesn't know anything.

It is unlikely that Russia will leave the project, according to the former commander of the International Space Station.

This is posturing by the Russians. It would take a long time to build their own station because they don't have the money. If they go this route, they don't have anything else, he said.

Analysis box by Jonathan Amos, science correspondent

It's not clear if the Russians are serious about withdrawing.

It would require a financial commitment from the Russian government to build their own outpost.

Engineers think that the modules can do a job through to the year 2030.

It would be a problem if Russia left. The partners are dependent on each other because of the station's design.

The US side of the International Space Station has the power, while the Russian side has the propulsion.

Europe, Japan and Canada will need to come up with other ways to boost the station higher in the sky if the propulsive capability is taken away. It can be done by American robotic freighters.

Russia and the US signed an agreement earlier this month to allow Russian cosmonauts to travel to the station on US spaceships, which appears to have been unaffected by the war in Ukraine.

All of us are flyers. Dr Chaio commanded the space station from 2004-5 and said that they learned to appreciate each other's views.

Other areas of cooperation between Russia and the west have been affected by the war in Ukraine. The European Space Agency ended its collaboration with the Russian government to launch a rover to Mars, and the Russian government stopped the launch of its own spaceship.

Russian cosmonauts on the ISS display the flag of the Luhansk People's RepublicImage source, Roskosmos
Image caption, Russian cosmonauts on the ISS recently displayed the flag of the self-declared Luhansk People's Republic

Russian cosmonauts have posed for pictures with the flags of pro-Russian regions in east Ukraine, for example, as a result of Russia politicising the space station.

If they didn't do it, they'd be in a lot of trouble, he said.

The Soviet Union and Russia have a long history of space exploration, and the first man in space in 1961, is a source of national pride.

Mr Borisov told Mr Putin that the new Russian space station would provide Russia with space-based services needed for modern life.

An image of France and the UK seen from the ISSImage source, ESA/NASA
Image caption, An image of France and the UK seen from the ISS
  • Russia
  • Space
  • International Space Station
  • Space exploration