A Republican senator stands on the floor of the US Senate. He poses a question: If Russia invades Norway, would the dispatch of 10 gallons of coal oil be enough to fulfill the US’s duty under Article 5 of the North Atlantic Treaty?
Of course not, he says, answering his own question and suggesting Article 5 would automatically entangle the US in European conflicts. The power to wage war should, according to the Constitution, belong exclusively to Congress.
These are not the words of Senator Paul Rand, who proposed an amendment expressing such concerns in July 2023. Nor are they the words of any other isolationist currently active in US politics. This hypothetical was floated by Senator Forrest Donnell in 1948, a year before the NATO agreement was signed.
The debate over Article 5, when it is invoked, and what its invocation implies, is as much debated today as it was then. While President Biden promises to “defend every inch” of NATO territory, his rival Donald Trump is far more ambivalent.
The Article 5 wording is vague. It states that an attack against one member “shall be considered an attack against them all.” What is quoted less often is that each member state only has an obligation to take “such action as it deems necessary, including the use of armed force.”
In other words, Article 5 does not commit member states to deploy military assets if an ally is attacked. It only commits them to some form of response.
The ambiguity was deliberate. It was crafted in response to US reservations about the depth of its military obligations as a member of a transatlantic defense alliance. The isolationist sentiment was still rife in the country, which had come to Europe’s aid in both world wars only after bitter internal debate.
US negotiators insisted on a vague formulation from the start. Secretary of State Dean Acheson clarified that it “naturally does not mean that the United States would automatically be at war if one of the other signatory nations were the victim of an armed attack.” Such a decision would only be taken as set out in the constitution, he said.
Acheson’s assurances were met with skepticism by Senator Donnell and others, and continue to be questioned today.
Following Russia’s full-scale invasion of Ukraine, President Volodymyr Zelenskyy made an urgent appeal to NATO members, arguing that the best protection for his country would be accession to the alliance. This suggestion stoked fears Article 5 might be immediately triggered, near-automatically forcing the deployment of NATO soldiers to the frontline.
Concerns re-emerged when President Emmanuel Macron suggested French troops might be deployed to Ukraine. Some said this too might trigger the collective defense article if French soldiers were killed in action (In fact, the article is concerned with protecting NATO territory, not NATO troops.)
Unlike the conjecture of 1948, we now have a clear precedent of what actually happens when Article 5 is invoked. It was engaged following the 9/11 attacks against the US in 2001 even though the dispatch of European troops to support US operations in Afghanistan was conducted by individual nations rather than the alliance.
While the UK joined the US in the military campaign against the Taliban on October 7, it took the German Bundestag until November to commit 3,900 troops. Spain never obtained parliamentary approval to send forces.
Responses varied based on the legislative process and national sentiment toward the war.
Over 75 years, alliance members have been engaged in numerous conflicts where Article 5 was not invoked.
While collective defense might not take the dramatic shape critics suppose, it does remain critical to NATO’s mission. But that was not always the case.
In the 1990s, after the Cold War, the continued relevance of Article 5 was brought into question. The West had prevailed, it was supposed, and there would be no need for such mutual defense assurances.
Today, in an era marked by renewed geopolitical tensions, Article 5 continues to serve as a vital deterrent, though it leaves open the door for less enthusiastic allies to send coal oil rather than armies.
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).
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.
War Without End
Russia’s Shadow Warfare
CEPA Forum 2025
Explore CEPA’s flagship event.
