UK & World News
Obama Warns Russia Against Crimea Invasion
US President Barack Obama has warned Moscow that any military intervention in Ukraine would be "deeply destabilising", as Kiev claims Russian troops have invaded.
He said: "The United States will stand with the international community in affirming that there will be costs for any military intervention in Ukraine.
"We are now deeply concerned by reports of military movements taken by the Russian Federation inside of Ukraine."
US officials say Mr Obama may cancel plans to attend the G8 summit in June if it is proved that Russia has sent troops into Crimea.
Russian President Vladimir Putin is scheduled to host the economic meeting in Sochi, the site of the recent Winter Olympics.
The administration official said the US was in discussions about the summit with European partners, adding that it was difficult to see how leaders would attend if Russia had forces in Crimea.
The US has also warned that discussions on deepening trade ties with Moscow may be halted in response to any Russian aggression.
Mr Obama's warnings come after Ukraine's Acting President appealed to Russia to stop "naked aggression" in the Crimean peninsula amid claims from Kiev 2,000 Russian troops have invaded.
Oleksandr Turchynov said: "I personally appeal to President Putin to immediately stop military provocation and to withdraw from the Autonomous Republic of Crimea ... It's a naked aggression against Ukraine."
Speaking after a private meeting at the United Nations, Ukraine's ambassador to the UN, Yuriy Sergeyev, said there was an "external presence" in Crimea "encouraging separatism".
He added he had told the council about "unspecified and armed forces of the Russian Federation on the territory of Ukraine".
US officials have told Fox News they see "evidence of air and maritime movement into and out of Crimea by Russian forces".
When asked about the claims, Russia's envoy to the United Nations, Vitaly Churkin, said Moscow was complying with agreements with Ukraine.
The pro-Russian prime minister of Crimea Sergei Aksenov, has appealed to Russia for help in keeping the peace there, and claimed control of all military, police and other security services in the region.
British Foreign Secretary William Hague will visit the country on Sunday and hold talks with Ukraine's new leaders.
Earlier on Friday, armed forces seized two airports in the region, but Moscow denies being behind the takeovers.
Ukrainian security sources claim they have regained control of Simferopol and Sevastopol airports amid earlier reports Russian forces tried to seize them.
Armed men were seen patrolling the perimeter at Simferopol, a civilian airport, and there were also reports Russian forces were blocking Sevastopol's military airport.
Despite the claims from Kiev, a military source quoted by the Interfax news agency said the armed men at Sevastopol had extended their control by taking over the runway.
Ukraine's State Border Guard Service said about 30 Russian marines from the country's Black Sea Fleet had taken up position outside the coast guard base in Sevastopol.
Moscow has said armoured vehicles were moving around Crimea for "security reasons".
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