Ukraine stepped up its efforts to join NATO after Russia invaded last year, arguing that the security assurances given by Moscow, Washington and London when it relinquished its nuclear arsenal to Russia in 1994 were clearly worthless.

While eastern European countries say some sort of a road map should be offered to Kyiv at a NATO summit in Vilnius on Tuesday and Wednesday, the United States and Germany are wary of any move that might take the alliance closer to war with Russia.

Russian President Vladimir Putin has cited NATO's expansion towards Russia's borders over the past two decades as a key reason for his decision to send tens of thousands of troops into neighboring Ukraine on Feb. 24, 2022.