How NATO factors into the Ukraine-Russia conflict

Ukraine is not a member of NATO, though the international security alliance has been a key player in its ongoing conflict with Russia.

Ukraine is not a member of NATO, though the international security alliance has been a key player in its ongoing conflict with Russia, which escalated to a full-scale invasion by Russian forces Thursday.

Since the United States helped form NATO, or the North Atlantic Treaty Organization, in 1949 to counter Soviet aggression in Europe, the alliance has grown to 30 member countries, including three former Soviet republics -- the Baltic states of Estonia, Latvia and Lithuania.

In 2008, NATO appeared to open the door to membership to two more former Soviet republics when its heads of government declared that Georgia and Ukraine "will become members of NATO."

Neither have formally received a pathway to eventual membership, with corruption concerns and a lack of consensus among members seen in part as holding back Ukraine's invitation. Russian President Vladimir Putin has demanded that Ukraine never join the alliance as he seeks to limit NATO’s presence in Eastern Europe.