Nato accuses Russia of violating Ukraine sovereignty
Nato has accused Russia of a "blatant violation" of Ukraine's sovereignty, saying it is engaged in direct military operations to support rebels.
Secretary-General Anders Rasmussen said that "despite hollow denials", it was now clear that Russia had illegally crossed Ukraine's border.
He said Nato would respect any Ukrainian decision on security, after its Prime Minister said he was putting the country on course for Nato membership.
President Vladimir Putin blamed the Ukrainian government for the crisis, comparing its siege of two cities held by separatists, Donetsk and Luhansk, to the siege of Leningrad by the Nazis in World War Two.