The prime minister of Ukraine said he will ask parliament to put the country on a course to join NATO.
Kyiv accuses Moscow of bringing troops into the country to support pro-Russian separatists.
NATO has released satellite images it claims show Russian combat forces in Ukraine.
“Russia continues to supply the separatist with tanks armoured vehicles, artillery and rocket launchers,” said Anders Fogh Rasmussen, NATO Secretary General. “Russia has fired on Ukraine from both Russian territory and within Ukraine itself.”
Ukraine is not a NATO member but meets regularly with what’s known as the NATO-Ukraine Commission.
NATO denied Ukraine a fast-track towards membership in 2008 when a previous pro-European government in Kyiv tried to pursue closer ties with the alliance.
Meanwhile Russian president Vladimir Putin said Kyiv’s operation in the eastern Ukraine region of Donbass is reminiscent of the Nazi siege of Leningrad.
“Unfortunately it reminds me of the events of World War II when German fascist occupiers surrounded our cities, for example Leningrad, and they executed the population of the villages,” said Putin.
US ambassador to the United Nations, Samantha Power, last night rejected Moscow’s claims that its forces were not involved in Ukraine.
“The mask is coming off,” she said. “In these acts, these recent acts, we see Russia’s actions for what they are: a deliberate effort to support, and now fight alongside, illegal separatists in another sovereign country.”