Nato is in crisis. Can history predict what happens next?

“If there's no response – or if it's a negative response – I think it will be very bad for the future of Nato.”

So said US President Donald Trump in March 2026, after asking European allies for their help in securing the Strait of Hormuz. This primary export route for most of the world's largest oil and gas fields had lately been declared closed by Iran as a response to US-Israeli military operations.

However, the response to the president’s call to aid to his European allies has, so far, been distinctly muted. No doubt this is in part because much of Europe is still reeling from the events at the start of the year.

Back in January, the American-led alliance was thrown into disarray by the president’s desire to assert control over Greenland – a semi-autonomous territory of Nato member Denmark. At the height of the crisis, with Trump adamant that the US “needed” Greenland “very badly”, the Danish prime minister Mette Frederiksen went so far as to say that "if the United States chooses to attack another Nato country militarily, then everything stops. That includes Nato, and thus the security that has been provided since the end of the Second World War."

Now, amid renewed transatlantic tensions stemming from the US–Israeli war with Iran, those key questions provoked by the recent Greenland debacle have resurfaced again: is Nato in crisis, and can it endure?

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On the latter, history does at least provide some reassurance.

In fact, surviving crises is something of a Nato speciality.

Nato’s troubled origins

The alliance initially coalesced in the immediate aftermath of the Second World War, a period characterised by growing concern in the west about the expanding influence and power of the Soviet Union.

In March 1946, Winston Churchill warned that an “Iron Curtain” had descended “from Stettin in the Baltic to Trieste in the Adriatic”. A year later, in an effort to “contain” the threat of Soviet expansion, President Harry Truman proclaimed the ‘Truman Doctrine’ asserting that the US would provide aid to democratic nations under threat from communist forces.

East-West tensions ramped up still further during the Berlin Blockade of 1948–49, after which 12 nations decided to establish a formal military alliance. The result was the North Atlantic Treaty Organization, which commits its signatories to the principle of collective defence.

It wasn’t long, though, before internal tensions began to emerge.

Nato from Suez to Iraq

Among the first major challenges to internal Nato cohesion arose during the Suez Crisis in 1956.

Built by the French, the Suez Canal – linking the Red Sea with the Mediterranean through Egypt – was a key strategic pipeline for trade, not unlike the Strait of Hormuz today. It was of particular importance to both the French and British empires because it drastically shortened the shipping route from Europe to Asia.

Aware of its strategic significance and keen to remove European influence and control, the nationalist Egyptian government of Gamal Abdel Nasser ordered that the canal zone be nationalised. In response, the British and French (with Israeli support) launched a military operation to seize the canal – an action that caused consternation in Washington. Angered by the lack of prior consultation, President Dwight D Eisenhower ultimately forced an Anglo-French withdrawal by threatening dire economic consequences.

Humiliated, the British prime minister Anthony Eden later resigned, while the French concluded that the Americans could not really be trusted. This was an “out of area” crisis because it occurred well away from the North Atlantic, but it still placed a significant strain on the Nato alliance.

Further internal Nato strains appeared in 1962 during the Cuban Missile Crisis, a nuclear standoff which pitted the US against the Soviet Union, with the former attempting to strongarm the latter into withdrawing its nuclear weapons from the communist Caribbean state.

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This time, the roles were reversed and it was the Europeans who were angered by an apparent lack of consultation – an issue of real concern given how dangerously close the world came to potential Armageddon.

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Similar European frustrations with US leadership later led to the alliance’s most significant crisis of the Cold War era. In 1966, unhappy with what he perceived as American influence in French foreign policy and the risk of being dragging into US-led conflict, President Charles de Gaulle removed the French military from Nato’s integrated military command. Rubbing salt in the wound, he also demanded that all US troops leave French soil.

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Elsewhere, even the often-proclaimed US–UK ‘special relationship’, for so long a cornerstone of Nato, came under strain during the 1960s, largely because of the war in Vietnam. Harold Wilson’s government refused repeated American requests to send troops to south-east Asia in support of the US, which jaundiced President Johnson’s view of the British as an ally.

However, despite their undoubted impact, none of these various Cold War crises led to Nato’s demise. The alliance survived and, indeed, played a key role during the heightened east–west rivalry of the 1980s.

Internal tensions re-emerged following the collapse of the Soviet Union in 1991. With the principal enemy now gone, the alliance found itself in uncharted waters. One consequence of this was transatlantic differences of opinion regarding Nato’s role and purpose. This later came to a head during the Global War on Terrorism, as it was labelled by the US.

Following a significant show of unity after 9/11 – which saw Nato invoke Article 5 (the mutual defence clause) for the first and only time in its history– a key point of divergence subsequently emerged around the American-led invasion of Iraq in 2003.

The UK and Poland lent Washington support, including troops, but the French and Germans vocally opposed the action. As a result, one commentator declared that the debate on Iraq had “provoked one of the worst transatlantic crises – and one of the worst intra-European crises – of the entire post-Second World War period”.

How Nato has endured

Over its lifetime, Nato – which now comprises 32 members – has seen plenty of internal disagreement and, on occasion, full-blown crisis. But no dispute has so far fatally compromised the alliance. This is because, fundamentally, Nato members do seem aligned on two key ideas.

First, the peace and prosperity of Europe and of the north Atlantic region is of the utmost importance.

And second, Nato remains the best mechanism through which to defend the interests and security of all of its members – including its most powerful, the US. This is why the Trump administration stepped back from the brink after staking verbal claims Greenland.

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As in earlier instances of internal tension, transatlantic trust has certainly been damaged. Real ideological distance remains between the current US administration and many European allies.

But the alliance endures because, beyond the disagreements, common interests remain strong. And as the history of Nato suggests, it’s often in those very moments of crisis that this inescapable fact returns to the fore.

As Churchill famously observed in the 1940s, “there is only one thing worse than fighting with allies, and that is fighting without them.”