NATO has accused Russia of a “blatant violation” of Ukraine’s sovereignty and engaging in direct military operations to support pro-Russian rebels.
The secretary-general of the North Atlantic Treaty Organisation, Anders Fogh Rasmussen, said “despite hollow denials”, it was now clear Russia had illegally crossed Ukraine’s border.
He said Nato would respect any Ukrainian decision on security, after its prime minister, Arseny Yatsenyuk, said he was putting the country on course for Nato membership.
Russian president Vladimir Putin blamed the Ukrainian government for the crisis, comparing its siege of two cities held by separatists, Donetsk and Luhansk, to that of Leningrad and Stalingrad by Nazi Germany in the Second World War.
Earlier, Mr Yatsenyuk said he was sending a bill to the Kiev parliament calling for Ukraine’s non-aligned status to be cancelled, paving the way for Ukraine to join Nato.
Mr Rasmussen called on Russia to cease military action, stop supporting the rebels and “take immediate and verifiable steps towards de-escalation of this grave crisis”.
He also indicated Nato would consider Ukraine’s application to join. He said: “I am not going to interfere with political discussions in Ukraine, but let me remind you of Nato’s decision at the Bucharest summit in 2008, according to which Ukraine will become a member of Nato, provided Ukraine so wishes and provided that Ukraine fulfils the necessary criteria.”
Nearly 2,600 people have been killed since April, the United Nations estimates, when Russia’s annexation of Crimea prompted rebels to take control of large parts of Donetsk and Luhansk regions. Heavy fighting continued yesterday near the port of Mariupol, on the Azov Sea, with government forces digging in as rebels tried to capture the city. The rebel attack raised fears Russia was seeking to create a land corridor to the Crimea.
Also yesterday, several European Union foreign ministers accused Russia of invading eastern Ukraine and said Moscow should be punished with additional sanctions.
Their meeting in Milan came one day after Nato said Moscow slipped at least 1,000 Russian soldiers and much heavy weaponry into Ukraine.
“We have to be aware of what we are facing: we are now in the midst of the second Russian invasion of Ukraine within a year,” said Swedish foreign minister Carl Bildt, referring to the March annexation of Crimea.
“We see regular Russian army units operating offensively on the Ukrainian territory against the Ukrainian army,” he said. “We must call a spade a spade.”
The foreign ministers were set to propose new sanctions against Russia for consideration at a summit of the EU’s 28 heads of state today in Brussels.
All options except military action will be considered to punish Russia for pursuing “the wrong path,” said Luxembourg’s foreign minister Jean Asselborn.
Ukrainian president Petro Poroshenko is set to meet the president of the European Commission, Jose Manuel Barroso, and summit chairman Herman Van Rompuy in Brussels today hours before the summit.
Both the United States and EU have targeted Russian officials, companies and its financial industry with sanctions. Russia banned food imports in reply, hitting a trade worth €10 billion (£8bn) to the EU. Any further move on sanctions needs the unanimous agreement of the 28 member states.
Russia is the EU’s third-largest trading partner and one of its biggest oil and gas suppliers.