What is NATO, and why isn’t Ukraine a member?

NATO ministers discuss boosting Ukraine — and avoiding a wider war

Ukraine is not a member of NATO, the military alliance of mainly Western countries united by a mutual defense treaty. But post-Cold War tension between the West and Russia over NATO — or the North Atlantic Treaty Organization — is at the heart of the current crisis.

Since 1999, 14 nations have joined NATO, including Hungary, Poland, Bulgaria and the Baltic states. Russia has demanded that the alliance stop expanding eastward — and bar Ukraine from joining. Ukraine’s government has said that it would like to enter the alliance, along with other nations that were once part of or allied with the former Soviet Union. In July of last year, Zelensky said Ukraine had proved itself time and time again that it was ready for the process to join NATO.

In 2019, Ukraine even enshrined its will to join the European Union and NATO in its constitution. But since the Russian invasion, Zelensky has made clear that this is not an immediate option for Ukraine.

NATO and U.S. officials in the last weeks have repeated the line that they will “defend every inch of NATO territory” with their full collective force.

While NATO Secretary General Jens Stoltenberg the day of the Russian invasion reiterated his support for Ukrainian sovereignty, he emphasized that there “are no NATO combat troops inside Ukraine at all … [and] we do not have any plans and intentional deploying NATO troops to Ukraine.”

Here is some essential background about NATO, and where Ukraine’s push for membership stands.

How joining NATO and the E.U. became Ukraine’s unattainable dream

What to know