The International Space Station is set to be shut down by the end of the decade thanks to the breakdown in ties between the U.S. and Russia in the wake of the Ukraine crisis.

The announcement came today as six Ukrainian soldiers were killed in an ambush by militants in the village of Oktyabrski in the breakaway east of the country.

At least 30 pro-Russian insurgents used grenade launchers and automatic weapons in the assault outside the town of Kramatorsk, which also left eight Ukrainian soldiers injured while the troops took part in a 'movement from a military base'.

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Threat: The International Space Station could close by the end of the decade thanks to U.S.-Russia tensions

Violence: Tensions continued to rise in Ukraine's east today as six Ukrainian soldiers were killed and eight more injured in an ambush by pro-Russian forces near Slaviansk (pictured)

Armed: Elsewhere near Slaviansk pro-Russian gunmen stood at checkpoints around the city

Damage: Ukraine's mostly Russian-speaking east is demanding greater autonomy from the Kiev government

In a statement to CNN, a military spokesman said: 'Our soldiers were attacked in an ambush. Terrorists attacked our land troops with grenades. The attackers were more than 30 people and set an ambush near the river," the ministry said.



'After a long shootout, six soldiers of The Ukrainian Armed Services were killed.'



Russia's deputy prime minister Dmitry Rogozin announced a series of punitive measures against the U.S. in response to sanctions imposed after Russia annexed Crimea.

The two countries have long co-operated closely on space exploration despite their clashes in foreign policy, but that era could now be coming to an end.

The International Space Station is manned by both American and Russian crew, but the only way to reach it is by using Russia's Soyuz spacecraft.

The U.S. is keen to keep the $100billion ISS flying until at least 2024, four years beyond its original target.

However, Mr Rogozin today said that Russia would reject the request, bringing the mission to an end in 2020.

Mourners have also taken to the streets of Krasnoarmeysk today as they hold funerals for pro-Russian activists killed by Ukrainian protesters over the weekend

Independence: Over the weekend Donetsk and Luhansk, two regions of Ukraine, asked to be annexed by Russia sparking violence when the National guard opened fire in Kransnoarmeysk (pictured)

Hyudych Vadim Yurievichq was one of those killed, and today his relatives, including his mother (C) held a funeral

'We are planning that we need the ISS until 2020,' said the official, who is on the sanctions list of both the U.S. and EU and recently set Russia the goal of colonising the moon.



'After 2020, we would like to divert these funds to more promising space projects.'

Pointedly, Mr Rogozin - in charge of the country's defence and space industries - noted that the 'Russian segment of the ISS can exist independently from the American one, but the American section cannot exist independently of the Russian one'.



Previously he has suggested that the Americans would have to use a 'trampoline' to get its astronauts into space without Russia.



Mr Rogozin - a hardliner who used to be Russia's ambassador to NATO - revealed: 'We have definite interest expressed by our American colleagues on extending the work of the ISS until 2024.



'But the Federal Space Agency, the Russian Academy of Sciences, and the Advanced Research Foundation, are ready now to propose some new strategic aspects, connected with the further development of space exploration after 2020.'

Attack: Separatist insurgents in the Ukrainian city of Slovyansk smash up machines in a gambling club

Violence: The militias have increasingly begun to dominate parts of eastern Ukraine

Uncompromising: The insurgents have expressed their opposition to control from the government in Kiev

His announcement was a response to U.S. sanctions which will deny export licences for any high-technology items that could aid Russian military capabilities. Mr Rogozin added that Russian rocket engines could no longer be exported to the U.S. if they will be used for military satellite launches. Moscow will also suspend the operation of GPS satellite navigation system sites in Russia, and seek to plant sites in the U.S. for the Russian equivalent of GPS, known as Glonass. Tensions in Ukraine have remained high over the past few weeks, as pro-Russian separatists in the east of the country have taken control of government buildings. Over the weekend, the regions of Donetsk and Luhansk both voted for independence from Kiev in referendums which were widely denounced as illegitimate. In a statement today, the Russian foreign ministry said that the poll results 'should be a clear signal to Kiev of the depth of the crisis' in Ukraine. It added: 'Moscow hopes the EU and United States will use their influence on the current leadership in Kiev so that issues of state structure and respect for the rights of regions are discussed soon.' In another sign that the violence is unlikely to abate soon, pro-Russian thugs were pictured using sledgehammers to destroy a gambling club in the city of Slovyansk. Hammers: The militants used sledgehammers to crack down on what they see as immoral behaviour Masked: The 'self-defence squads' have often taken to disguising their true identities Defiant: Vladimir Putin's government today announced new retaliatory measures against U.S. sanctions

In a bizarre incident at the weekend, Mr Rogozin angrily accused Romania and Bulgaria of seeking to force down an official government aircraft as he returned from the breakaway pro-Russian region of Transnistria.

He threatened to fly next time in a TU-160 supersonic strategic bomber. Bucharest issued a protest over his comments but the row deepened today with Mr Rogozin threatening harsh diplomatic measures against Romania, having earlier made a similar threat against Moldova, the country from which he was seeking to fly back to Moscow.

'Romania said today via Prime Minister Victor Ponta that if the premier, not the president, were in charge, he would use a destroyer to land our plane in Romania. There is nothing to talk about with them after this,' said Mr Rogozin.

'It is one thing to introduce sanctions regarding people so that they do not come and not to issue visas but to land forcefully a plane with several members of the Russian government on board using military aviation is beyond jokes and various half-serious conversations. The reaction should be most harsh.'

Breakaway: Denis Pushilin, centre, claims to be head of the 'Donetsk People's Republic' in eastern Ukraine

Patrol: A tank driven by Ukrainian soldiers on the roads near Slovyansk

He claimed: 'The issue is not physical safety of a certain person - the issue is that they put under sanctions the right of Russian citizens, including those in the country's authorities and representatives of the

Russian government, to fly transit over air space of these countries.

'The pilot has informed me that when the jet entered air space of Bulgaria and Romania, dispatchers got in touch with him and demanded to report whether persons who are in the EU and U.S. sanctions list are on board.'

On the way back the Romanian authorities refused to let the Russian delegation's aircraft to go through its air space, Mr Rogozin added.