This Western mutual-defense alliance, which sees an attack on one member as an attack on all, is central to the war in Ukraine, even though Ukraine is not a member.
Though Ukraine has been pressing for years to become a member of the North Atlantic Treaty Organization, or NATO, it hasn’t been granted membership. Still the 73-year-old defense alliance’s eastward-growing footprint is among the reasons President Vladimir V. Putin has cited for invading Ukraine.
Even though Ukraine is not a member of NATO, other member states have been sending arms and supplies as the country tries to fight off the Russians.
But, on Friday, NATO foreign ministers rejected any possibility of intervening against Russian forces in Ukraine, whether on the ground or in the air, the alliance’s secretary general said.
“Allies agree we should not have NATO planes operating over Ukrainian airspace or NATO troops operating in Ukrainian territory,” Jens Stoltenberg, the secretary general, said at a news conference after a meeting of foreign ministers.
Here’s what you need to know about the alliance and, in particular, the no-fly zone it has so far abstained from providing.
Why did NATO reject a no-fly zone in Ukraine?
For now, NATO declined to impose a no-fly zone, and some leaders have said they are not willing to issue one, fearing that doing so could escalate tensions with Russia.
Creating a no-fly zone over Ukraine would require deploying NATO fighter planes and possibly “shooting down Russian planes,” Mr. Stoltenberg said. That, he warned, could lead to “a full-fledged war in Europe, involving many more countries and causing much more human suffering.”
Mr. Zelensky, speaking in a video shared on social media, criticized that decision, calling the summit “weak” and “lost.” He said that NATO’s refusal to take such a step gives Russia a “green light” to continue its invasion of Ukraine.
What is NATO?
The mutual-defense alliance was established in 1949, after World War II, and included United States, Canada, and 10 European countries.
The treaty for which the alliance is named has 14 articles, by which all NATO members must abide. One of the most important articles in the treaty is Article 5, which declares that an attack against one member state is an attack against them all.
That article placed Western Europe under U.S. protection in the face of a Soviet Union that was cementing its domination over Central and Eastern Europe and appeared then only to be growing in power and ambition.
After the Soviet Union’s collapse in the early 1990s, the alliance took on a wider role. NATO forces — made up of troops volunteered by member states — operated as peacekeepers in Bosnia in the 1990s, and bombed Serbia in 1999 to protect Kosovo, where the alliance still has troops.
Which countries are in NATO?
In addition to the United States and Canada, 10 other countries became part of NATO in 1949, including: Belgium, Denmark, France, Iceland, Italy, Luxembourg, the Netherlands, Norway, Portugal, and Britain.
Russia-Ukraine War: Key Things to Know
Evacuation efforts under attack. As Russian forces continued shelling Ukraine, at least four people, including a mother and her two children, were killed outside Kyiv as they tried to get to safety. In the besieged port city of Mariupol, a planned evacuation was halted for a second consecutive day.
Since then, 18 more European powers have joined: Albania, Bulgaria, Croatia, the Czech Republic, Estonia, Germany, Greece, Hungary, Latvia, Lithuania, Montenegro, North Macedonia, Poland, Turkey, Romania, Slovakia, Slovenia and Spain.
Other European countries have, over the years, avoided joining NATO, including Sweden and Finland.
What is a no-fly zone?
A no-fly zone bans aircraft from certain areas. Ukraine is asking that aircraft be barred from its skies, which would, in theory, stop aerial bombardment by Russia.
No-fly zones are used over government buildings or public places for security reasons. In the United States, for example, aircraft are prohibited from flying over the White House, the National Mall and the vice president’s residence in Washington. No-fly zones like this are not controversial.
However, they can be contentious if they are used to stop military aircraft from engaging in hostile actions as they were in Iraq. And Mr. Putin said Saturday that Moscow would view any Western attempts to impose a no-fly zone over Ukraine as “participating in the armed conflict” against Russia.
Peter Robins contributed reporting.
