The current NATO members entered the coalition in waves:
- 1949: Belgium, Canada, Denmark, France, Iceland, Italy, Luxembourg, Netherlands, Norway, Portugal, The United Kingdom, The United States
- 1952: Greece, Turkey
- 1955: Germany
- 1982: Spain
- 1999: Czech Republic, Hungary, Poland
- 2004: Bulgaria, Estonia, Latvia, Lithuania, Romania, Slovakia, Slovenia
- 2009: Albania, Croatia
- 2017: Montenegro
- 2020: North Macedonia
Of note are the 1999, 2004, and 2009 members—countries in the former Warsaw pact that acceded to NATO.
Former Warsaw pact countries, especially Russia's neighbors among the 2004 cohort, did not experience a military intervention from Russia to avoid their NATO membership. Had Ukraine swiftly been accepted to (or alternatively swiftly been rejected from) NATO, it could have (speculatively) avoided the 2022 Russian invasion.
Which begs the question if the process of admitting Ukraine into the NATO was unusually long or took the same time as usual.
How long did it take Warsaw pact countries until their NATO memberships were ratified?
- Why did the former SSR countries like Lithuania, Estonia, and Latvia face no trouble joining NATO and EU?
Some relevant facts:
- 2006 is the earliest I could find when chatter regarding Ukraine's membership had started. Oddly, it appears that the discussions were triggered by an invitation—from George W. Bush and Condoleeza Rice—and not, as might be expected, by Ukraine courting NATO for membership.