Following are the steps that Ukraine has taken on its way to NATO membership, a possible compromise over the next steps - and Russia's view of the developments.
AN UNMAPPED PATHIn 2008, NATO agreed at a Bucharest summit that Ukraine - which was part of the Moscow-ruled Soviet Union until its 1991 demise - could eventually join the alliance.
Moscow then illegally annexed Crimea from Ukraine in 2014 and backed separatist proxies in eastern Ukraine.
It is cited as one of the main reasons why Ukraine cannot join NATO while in conflict with Russia, as this might immediately draw the alliance into an active war.
Moscow has said it would cause problems for many years to come if Ukraine joined NATO and has warned of an unspecified response to ensure its security.
Persons:
Vladimir Putin, Jens Stoltenberg, Stoltenberg, Ukraine's, Volodymyr Zelenskiy, Sabine Siebold, Philippa Fletcher
Organizations:
NATO, Russia, Kyiv, Atlantic Treaty Organization, Soviet Union, West, NATO's, Kremlin, Thomson
Locations:
BRUSSELS, Ukraine, Moscow, Washington, London, Russia, Vilnius, United States, Germany, Russian, Russia's, Bucharest, Soviet, Crimea, Kyiv, NATO, Europe, Finland, Sweden, Britain, NATO's Washington Treaty