In 1992, following the fall of the Soviet Union, Francis Fukuyama published The End of History and the Last Man. He argued that Western liberalism had won the battle for geopolitical dominance and, with this victory, the world had reached its final form of government. All war would cease.
Three years later Stanley R Sloan, then working for the Congressional Research Service, published NATO’s Future: Beyond Collective Defense. He wrote that the end of the Cold War meant Article 5, which states an attack against one NATO member is an attack against all, had been put in NATO’s “back pocket” and Article 4 would take center stage instead.
“NATO’s day-to-day activities during the next period of history are likely to focus increasingly on the new ‘risks’ and less and less on territorial defense,” he argued.
Article 4 commits NATO parties to “consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the Parties is threatened.”
When the article is invoked, NATO members meet to consult in the North Atlantic Council. This may result in coordinated action from allies, though it does not have to.
Originally, it was included in the NATO treaty to cover Europe’s declining colonial interests. Unlike Article 5, it does not specify a territorial scope for any threat, allowing members to call on NATO resources and support in their overseas territories.
In practice, Article 4 was never used in this way, nor did it replace Article 5 after the 1990s. Most European colonies won their independence from the 1940s-1960s and the resurgence of geopolitical tensions in the 21st century means Article 5 remains the alliance keystone.
Instead, Article 4 has morphed into a tool used by member states when they feel threatened, even if not under direct attack.
Since its first formulation, the article has expanded to include threats from terrorism and organized crime. It also provides a mechanism for allies to exchange information and establish a common approach against such threats.
Since NATO’s creation in 1949, Article 4 has been invoked seven times, all in the 21st century. It was always for one of two reasons: the Russian threat in Eastern Europe, or Turkey’s fears over tensions in the Middle East.
The most invocations came from Turkey, the country that from 2022 to 2023 worked to block Finnish and Swedish membership (before ultimately relenting.) In 2003, pointing to a rising threat from neighboring Iraq, Turkey became the first ally to make use of Article 4.
During the Syria conflict, starting in 2012, Ankara asked for support under Article 4 three times. It also called for consultations following terrorist attacks in 2015. NATO’s responses varied, both offering direct support for example in 2012, while restricting involvement to consultations at other times.
In 2014, following Russia’s annexation of Crimea, Poland became the second nation to invoke Article 4. After Moscow’s full-scale invasion of Ukraine in 2022, it was joined by seven other capitals requesting NATO consultations under the provision.
The obligation to consult when an ally feels threatened might seem less than pugnacious given it is a military alliance, but it is arguable that Article 4 has played a more consistent role in the West’s response to military threats as they arise than Article 5.
Now that history has returned with a vengeance, there is good reason to believe allies will respond to threats before they become existential. Article 4 allows for that.
Clara Riedenstein is an incoming graduate student at Oxford University’s Department of Politics and International Relations and a research assistant with the Digital Innovation Initiative team at the Center for European Policy Analysis (CEPA).
Lucy Matthews attends American University and is currently an intern with the Digital Innovation Initiative at the Center for European Policy Analysis (CEPA).
Europe’s Edge is CEPA’s online journal covering critical topics on the foreign policy docket across Europe and North America. All opinions expressed on Europe’s Edge are those of the author alone and may not represent those of the institutions they represent or the Center for European Policy Analysis. CEPA maintains a strict intellectual independence policy across all its projects and publications.
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