Explainer: NATO Articles 4 and 5

Poland is increasing the readiness of some of its military units, government officials said Tuesday, after unconfirmed reports that stray Russian missiles killed two people near the country’s border with Ukraine.

Polish President Andrzej Duda, who spoke with U.S. President Joe Biden and NATO chief Jens Stoltenberg, was reportedly considering whether to call urgent consultations with NATO leaders under the alliance’s Article 4. The article allows NATO members to bring any issue of concern, especially regarding security, for discussion at the North Atlantic Council.

A NATO official, speaking on condition of anonymity, said the alliance was looking into the reports, as was the U.S. National Security Council, The Associated Press reported. The Russian Defense Ministry has denied the allegations.

What is NATO Article 4?

The article allows NATO members to bring any issue of concern, especially regarding security, for discussion at the North Atlantic Council. Article 4 does not mean there will be direct pressure to act.

Under Article 4, any member state can convene a meeting of NATO members to “consult” when it feels its independence or security is threatened. In practice, it has rarely been used; regardless, it sends a strong message to the greater world that NATO is concerned about the situation.

What is NATO Article 5?

The principle of collective defense — meaning that an attack against one ally is considered as an attack against all allies — is the keystone of NATO. It states that an “armed attack” against one member is an attack against all and sets in motion the possibility of collective self-defense.

However, it commits each NATO member to “assist the party or parties so attacked” and to take “such action as it deems necessary, including the use of armed force.” It does not automatically result in military action.

How would NATO decide to invoke either article?

In theory, Articles 4 and 5 could be invoked only at the request of a NATO member.

Since the alliance’s creation in 1949, Article 4 has been invoked seven times, most recently on February 24, 2022, when Bulgaria, Czechia, Estonia, Latvia, Lithuania, Poland, Romania and Slovakia requested to hold consultations under Article 4 following the Russian invasion of Ukraine.

Article 5 has been invoked only once, immediately following the September 11, 2001, terror attacks against the United States.

Radio Free Europe/Radio Liberty contributed to this article. Some material for this report came from Reuters and The Associated Press.
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