NATO Allies Have Been Discussing Invoking Article 4: What to Know

Denmark on Sept. 26 confirmed that there are no plans to invoke NATO’s Article 4, after drone incursions into its airspace earlier this week.

“Article 4 has been activated nine times in NATO’s entire history, and twice recently in relation to Poland and Estonia, so we have no reason to do so,” Foreign Minister Lars Lokke Rasmussen told reporters.

On Sept. 22, Sept. 24, and Sept. 25, Denmark was forced to close airports after drone sightings.

Danish Prime Minister Mette Frederiksen linked the incidents to a series of suspected Russian drone incursions across Europe amid Russia’s ongoing war with Ukraine, without citing evidence.

Russia denied involvement.

As a result, and up until Sept. 26, Denmark had been considering whether to invoke Article 4.

While many are familiar with NATO’s Article 5—the mutual defense pledge—people may be less aware of Article 4.

Here is what Article 4 is and how it works.

What Is Article 4?

Article 4 is the shortest of all the clauses in the North Atlantic Treaty, which was ratified in Washington on April 4, 1949.

It states, “The parties will consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the parties is threatened.”

This means that if a NATO ally has an issue of concern, particularly regarding security, it can table a discussion at the North Atlantic Council, NATO’s principal political decision-making body.

Members can discuss the issue, which can potentially lead to some form of joint decision or action.

It effectively puts the issue formally on NATO’s agenda.

However, invoking Article 4 and discussing it does not automatically lead to any action.

Why Are Countries Invoking Article 4?

Most recently, countries have invoked Article 4 after they have reported incursions into their airspace. They have accused Russia of being behind the incidents.

Poland invoked Article 4 on Sept. 10 after it downed several Russian drones that had entered Polish airspace.

Then, on Sept. 23, NATO allies met following an Article 4 request from the Estonian government, after three Russian fighter jets entered Estonia’s airspace.

Russia has denied NATO accusations that it has repeatedly violated its airspace.

How Many Times Has It Happened?

Since NATO’s formation in 1949, Article 4 has been invoked nine times.

The first time was on Feb. 10, 2003, when Turkey asked for consultations with the North Atlantic Council over concerns of threats to its security as a result of escalating tensions in neighboring Iraq in the weeks leading up to the Iraq War.

In fact, Turkey is the NATO member that has triggered Article 4 the most often, five times in total.

More recently, Eastern European nations have called for consultations in the context of the Russia–Ukraine War.

On Feb. 24, 2022—the day Russia began its invasion of Ukraine—Bulgaria, the Czech Republic, Estonia, Latvia, Lithuania, Poland, Romania, and Slovakia requested a consultation as a result of the conflict on the defense alliance’s eastern front.

Then, in the span of two weeks in September, Article 4 was triggered by Poland and Estonia.

What Is Article 5?

Article 5 is the component of the treaty that most people are familiar with.

It is the collective security guarantee, and it is considered a key part of the alliance.

In it, the members agree “that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all.”

NATO explains in more detail on its website that when Article 5 is invoked, “Allies can provide any form of assistance they deem necessary to respond to a situation.”

“This is an individual obligation on each ally and each ally is responsible for determining what it deems necessary in the particular circumstances,” the website states.

This assistance “is not necessarily military,” NATO stated.

The response depends on the resources of each member state, and “it is therefore left to the judgment of each individual member country to determine how it will contribute.”

According to NATO, Article 5 was invoked “for the first and only time in its history after the 9/11 terrorist attacks against the United States.”

Does Article 4 Automatically Lead to Article 5?

No, it does not.

Bob Deen, an analyst at the Clingendael Institute think tank in The Hague, Netherlands, told The Associated Press that Article 4 is “designed to promote better coordination and understanding within the alliance on external threats.”

“It gives all allies the opportunity to urgently put certain threats or developments on the agenda of the North Atlantic Council,” he said.

Deen said that while Article 4 is related to Article 5, it is “not necessarily a ‘stepping stone.’”

Article 4 also does not need to be invoked in sequence before Article 5.

The Clingendael analyst said that in the case of the 9/11 attacks, Article 5 was triggered directly.

“In other words: Article 4 can be invoked without triggering Article 5, and vice versa,” he said.

The Associated Press, Reuters, and Rachel Roberts contributed to this report.