J.D. Capelouto
J.D. Capelouto
Updated Nov 15, 2022, 9:32pm EST

What is Article 4? Explaining NATO's options after Russian-made missile hits Poland

J.D. Capelouto is a Breaking News reporter. You can reach him at jcapelouto@semafor.comSign up for Flagship, our daily newsletter that distills what’s happening in the world into a concise, insightful morning read.


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After authorities said a Russian-made missile fell on a Polish village and killed two people Tuesday, Polish leaders said they were considering invoking Article 4 to spur action from NATO, the 30-nation alliance Poland belongs to.

Here's a rundown of what that treaty provision does, and what could happen after Tuesday.

The NATO logo in Brussels.
REUTERS/Yves Herman/File Photo
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Polish President Andrzej Duda said in a televised address on Tuesday evening that it was very likely that Poland would invoke Article 4 at a meeting Wednesday after the missile crossed into Polish territory, just three miles from the Ukrainian border. Polish Prime Minister Mateusz Morawiecki's office also said Tuesday it was talking with allies about potentially invoking Article 4. Ukraine isn't a member of NATO, but Poland is.

Article 4 allows the NATO member countries to "consult" whenever one of them feels "the territorial integrity, political independence or security of any of the Parties is threatened." It doesn't mandate or guarantee any sort of action or coordinated defense response.


Several Eastern European countries triggered Article 4 at the beginning of the war in Ukraine, since some share a border with Ukraine. NATO held talks and pledged financial and military support to Ukraine, thought the member states did not send their own troops.

Polish authorities have not mentioned invoking NATO Article 5, which is considered a cornerstone of the alliance and states that any "armed attack" against a NATO member "shall be considered an attack against them all."

The invocation of Article 5 doesn't mean every allied country must respond with military force. Instead, they can decide for themselves how to react. Article 5 has only been invoked once in NATO's history, after the 9/11 terrorist attacks on the U.S.

After the Russian missile hit Poland Tuesday, several experts said they expect Article 4 to be a logical course of action.

Ben Hodges, the former commanding general of U.S. Army operations in Europe, said Article 4 talks would be appropriate if the incident was not a deliberate attack on Poland.

Latvian Defense Minister Artis Pabriks also said his "first reaction" would be to put Article 4 in place.