Russia announces decision to halt export of crucial rocket engines in response to US sanctions over annexation of Crimea

Russia's deputy prime minister, Dmitry Rogozin, has announced it will halt the export of rocket engines crucial to the US military defence and space programmes.

The move marks a serious deterioration in US-Russian cooperation in space, which for two decades had remained largely above Earthly politics. It could prove a serious set back for the ailing US space programme.

The Russian RD-180 engine has been in production since 1999. The US has imported more than forty of them to power its Atlas V rockets into space.

Designed to be expendable, the RD-180s are not recovered and refurbished after use, so a constant supply is needed to keep up with the US launch manifest.

Although Nasa relies on the Atlas V to launch some of its deep space probes, such as the Curiosity rover currently operating on Mars, most are used to put AmericanUS spy satellites and other classified payloads into space.

Under the new restrictions, it is only rockets for military rather than civilian launches that would be disallowed. But in practice it will make it difficult for the US to import any of the engines because it will hard to prove the hardware is not destined for a military programme.

Russian's move is the latest step in an escalating series of sanctions affecting space co-operation brought about by the Russian annexation of Crimea.

On 3 April, Nasa announced it was suspending its partnership with Russia over all space activities apart from the International Space Station (ISS).

It was a risky move because the US lost the ability to launch its own astronauts with the abandonment of the space shuttle programme in 2011.

Private companies are now developing replacement capsules but flights carrying astronauts will not happen until December 2015.

Until then, the US has no choice but to rely on the Russians.

Now Moscow has signalled the end of the ISS collaboration, too. Russian news agency Interfax reported on Tuesday that Moscow would not extend its collaboration on the ISS beyond 2020.

The countries have been working together on the ISS since 1993, following the collapse of the Soviet Union. "After 2020, we would like to divert these funds [used for ISS] to more promising space projects," said Rogozin. These could include collaborations with the Chinese on other space stations or even moon bases.

While the space station is the most visible sign of the superpowers' collaboration, it is the loss of the RD-180 engines that will really hurt, according to space commentator Brian Harvey, who has reported on the Russian space programme since the 1970s.

"For the Americans not to take RD-180s any more would probably be quite disruptive of their space programme in the medium-term," he says. This is because of the time it would take to develop a replacement.

"Most people don't realise just how advanced and powerful Russian rocket engines are," says Harvey.

He estimates that it would probably take five years for the US to build up the necessary technologies and manufacturing expertise to replace the engines. But it does open another opportunity for private companies including PayPal founder Elon Musk's Space X which is developing the Dragon Capsule to ferry people and cargo to the ISS.

On 30 April, Space X filed a protest with the US court of federal claims over bulk-buying of the Russian rockets. A temporary ban on importing the RD-180s was ordered because the company responsible for their manufacture, NPO Energomash, was said to be under the control of Rogozin, who is on the US sanction list over Ukraine.

Following an appeal by the US State, Treasury and Commerce departments, the US federal court dissolved the ban but now Rogozin has announced his own prohibition, the US may be forced to develop a replacement engine after all.

In the meantime the US must rely on already bought RD-180s and stocks are dwindling. The US was expecting the delivery of another five this November but the restriction places these in doubt.

"With a bit of sense, the present episode in Ukraine will be over before that happens," says Harvey.