How Donald Trump’s re-election would threaten NATO’s Article 5

Editor’s note (February 14th 2024): This piece was updated after Jens Stoltenberg, NATO’s secretary-general, announced that 18 of the alliance’s 31 members would meet its 2% of GDP defence-spending target in 2024.

AS PRESIDENT, DONALD TRUMP made no secret of his dislike of NATO. In 2018, at a summit of the military alliance, he threatened that America would “go its own way” if other members did not increase their defence spending. He is said often to have talked privately about leaving NATO. But on February 10th, at a rally in South Carolina, Mr Trump went further. He claimed, no doubt apocryphally, that the “president of a big country” asked him: “Well, sir, if we don’t pay and we’re attacked by Russia—will you protect us?” Mr Trump says he replied: “You didn’t pay? You’re delinquent… No, I would not protect you. In fact I would encourage [Russia] to do whatever the hell they want.”

During his first term, European heads of government worried about Mr Trump undermining America’s commitment to the fifth clause of NATO’s founding document, the Washington Treaty of 1949. Article 5 states “that an armed attack against one or more [members]… shall be considered an attack against them all” and that members would assist the victim or victims of such an attack “forthwith”. The only time that Article 5 has been invoked was after the attacks of  September 11th 2001 with the result that NATO led a security mission in Afghanistan for a decade from 2003.

Article 5 states that NATO’s response may include armed force, but it does not mandate it. What the alliance promises is to take “such action as it deems necessary” to restore and maintain security. That could be anything from nuclear war to a stiff diplomatic protest. Another ambiguity—which has concerned members since Russia’s annexation of Crimea, part of Ukraine, in 2014—relates to so-called “hybrid warfare”. This combines propaganda, corruption, subversion, espionage, the exploitation of economic and energy dependency, diplomacy and the use of irregular military forces (the “little green men” who popped up in Crimea). Although Ukraine is not a NATO member, Russia’s attack illustrated a problem for the alliance: how to identify where the threshold for a forceful response should be, and how to calibrate it to avoid escalation into a full-on armed conflict.

Despite Russia’s conventional aggression against Ukraine in 2022, those concerns have not entirely gone away. Vladimir Putin, Russia’s president, still appears to regard a direct attack on NATO territory as too risky. But if he becomes emboldened by gaining the upper hand in Ukraine, he might be tempted to test where NATO’s threshold for using force lies, for example by blockading the Baltic states, orchestrating a large cyber attack, or attacking the Suwalki gap, the NATO corridor between Belarus and Kaliningrad, a Russian exclave. Were Mr Trump to become president again, that temptation would be far stronger.

image: The Economist

Since Russia’s full-scale invasion of Ukraine the defence budgets of NATO’s European members have risen sharply. Led by Poland, spending on military equipment has risen by 25%, and the number of NATO members reaching the target of spending at least 2% of GDP on defence is now 11 out of 31 (see chart).  The alliance expects that figure to rise to 18 by the end of 2024.

Yet it seems unlikely that any realistic level of European defence spending would mollify Mr Trump. Instead, Europe is beginning to confront the unthinkable: that the underpinning of Europe’s security by American military might, a given for 75 years, can no longer be relied upon. This shift is happening at a moment of greater peril for Europe than at any time since the height of the cold war, when the continent’s defences were much more formidable.

Some may say that this is alarmist. After all, Mr Trump did not pull America out of NATO in his first term. In any case, bipartisan legislation passed late last year obliges any president who wants to quit the alliance to secure a two-thirds majority in the Senate or an Act of Congress, a deliberately high bar.

Yet for others, such reassurance rings hollow. In his first term, Mr Trump was largely constrained by defence secretaries and national security advisers who were committed to NATO. If he won a second he would probably make appointments that would ensure he was no longer hemmed in. Even if he found he could not formally take America out of NATO, Mr Trump could fatally erode its commitment to treaty obligations by pulling American forces out of Europe, failing to extend American nuclear deterrence to Europe and casting doubt on his commitment to order American troops to fight in Europe’s defence. Under such circumstances, Mr Putin would have been granted his dearest wish—the shredding of any practical meaning from Article 5 as far as America was concerned.