Jens Stoltenberg was secretary general of NATO during a particularly turbulent decade, 2014 to 2024. During his tenure, European unity was shaken by Brexit, the alliance’s withdrawal from Afghanistan, Russia’s frontal attack on Ukraine, Turkish and Hungarian opposition to Finnish and Swedish efforts to join NATO, and exacerbation of global tensions by increasingly militaristic China. As if these challenges were not enough, in 2018 president Donald Trump threatened to withdraw the US from the alliance, which would have undermined its very existence.

Stoltenberg’s term as head of the alliance was the second longest, attesting to members’ confidence in his leadership. He was due to step down in 2022 but, following Russia’s attack on Ukraine, his tenure was extended twice, finally to late 2024. Before steering NATO, Stoltenberg had served as prime minister of Norway and in other ministerial positions; now he’s back in Norway as finance minister.

In his newly published memoir, On my watch, Stoltenberg provides a candid account of his struggles to address global security challenges and keep NATO relevant. By any standards, the book is remarkably frank. And, unsurprisingly, it centres around two issues: Russia’s war on Ukraine, and Stoltenberg’s efforts to keep Trump, during his first term, from pulling the US from the alliance.

At the outset of his term, when Russia’s aggression against Ukraine was in its early stages, Stoltenberg tried to get NATO members to help Ukraine, and from the outset he encountered resistance. Even after Russia’s full-scale invasion in 2022, key NATO members were wary of escalating the conflict, and allies struggled to provide Ukraine with offensive weapons, including tanks, fighters and long-range missiles.

Relations with the US came to a head at the NATO summit in May 2018. In the run-up to the meeting, Trump had blown hot and cold about the need for the alliance, demanded that other members step up their military spending and threatened to withdraw the US.

Stoltenberg provides a riveting behind-the-scenes account of the summit, and the lengths to which he and Dutch prime minister Mark Rutte—who would succeed him as secretary general—went to appease Trump and coax members into increasing their military budgets.

At a pre-summit breakfast that ‘felt like an eternity’, Trump turned what was supposed to be a closed-door meeting with NATO’s leadership into an occasion for criticising members in front of the media for not meeting commitments.

The summit itself kicked off with Trump reiterating how unhappy he was with NATO. To calm the atmosphere, Rutte informed the meeting that year-on-year NATO members had increased their military expenditure by $33 billion, a figure that had been carefully worked out with members, and stressed that this was thanks to Trump’s leadership.

This seemed to satisfy Trump, who prior to the closing passed Stoltenberg a note saying: ‘Secretary general, if you can say that NATO allies have significantly increased their defence expenditure thanks to me, then I think we can agree’. Stoltenberg and Rutte had carefully planned their moves in advance, and Rutte’s skill in working with Trump was key to his subsequent appointment as Stoltenberg’s successor.

Stoltenberg remains unsure just how close the US came to withdrawing but notes that during the summit his team got wind that the members of the US delegation had packed their bags and were ready to leave. The situation was dire, and Stoltenberg reminds us that if the US had left NATO, without its security guarantees the alliance would in practice have ceased to function.

The story, however, did not end there, and US demands raised their head again in February 2019. Prior to Trump’s state of the union address, the White House informed NATO that two versions of his speech had been prepared. In one, Trump would say that he wanted to withdraw from NATO, and in the other that the US would only protect countries that spent 2 percent of their GDP on defence.

Stoltenberg quickly arranged to be interviewed by Fox News where he reiterated that NATO members had upped their defence spending thanks to Trump. The interview was broadcast to a wide audience, but according to Stoltenberg he was speaking to only one loyal viewer. The interview worked and Trump delivered the second version of his speech.

During his decade at NATO’s helm, Stoltenberg succeeded admirably in holding the alliance together. But by his own reckoning he failed on two counts. In Afghanistan NATO should have focused on combatting terrorism rather than getting into nation building, and it should have withdrawn earlier. And his biggest regret is that NATO did not provide Ukraine with stronger support in 2014 when Russia’s little green men occupied Crimea. Stoltenberg speculates openly whether this might have helped to prevent the war. Following Russia’s 2022 attack, he often asked himself whether NATO could have done more.

For security professionals and generalists alike, Stoltenberg’s forthright memoir is a gripping read.