How long did it take Warsaw pact countries until their NATO memberships were ratified?

Question

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?

Related:

• Why did the former SSR countries like Lithuania, Estonia, and Latvia face no trouble joining NATO and EU?

Edit:

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.

Answer 1

There is no waiting list with numbers to draw, or required waiting time. Once the existing NATO members approve a new candidate, the treaties can be signed rather quickly.

NATO expects applicants to meet economic, democracy, and rule of law criteria, which Ukraine did not meet fully, and to resolve outstanding border issues. As NATO understands itself, it is a mutual defensive alliance for the members, not as a global policeman or protector of the weak -- even if the appearance might have been different in the last few decades.

Answer 2

The intention of Poland, Czechoslovakia and Hungary to join NATO became official with the formation of the Visegrád group in 1991. It then took 8 years until Poland, Czech and Hungary became NATO members, and 13 years for Slovakia.

The same summit in 1999 which admitted Poland, Czech and Hungary also formally passed the "Membership action plans" for the 2004 batch and 2009 batches which were admitted 5 years later and 10 years later respectively. But the plans to admit them were probably known to Russia much earlier than 1999. The admittance of the Baltic states of Estonia, Lativa and Lithuania was especially threatening to Russia, because two of those countries share a land-border with them. Russia did protest this extension of NATO, but did not intervene. It was the time where Russia was still getting its own affairs in order after the dissolution of the Soviet Union, so they probably didn't have the strength to intervene at that point in history.

Montenegro was perhaps the fastest ascension. It only took 3 years between their declaration of independence in 2006 and joining NATO in 2009.

Macedonia, on the other hand, was an outlier in the opposite direction. Their ambitions to join NATO became official in 1995, but it took 25 years until their admission (mostly because Greece would not let them join until they changed their name to "North Macedonia" to renounce their implied claim on the Greece administrative region also named Macedonia).

If we assume that Ukrainian NATO membership was officially on the table after the 2014 Revolution, then that would have been pretty exactly 8 years ago. Which is already par for previous NATO extensions. And if we further keep in mind that Ukraine had several internal issues (uncertain political stability after the revolution, unresolved civil war in the east) and external issues (a much stronger Russia, the territorial conflict around Crimea), it is pretty understandable that NATO did not fast-track the process. But this is a topic for another question.

For more information on the NATO eastern expansion, check the Wikipedia article Enlargement of NATO.