A decade at the helm of NATO: Why is replacing Jens Stoltenberg so difficult?

That’s because the Norwegian’s term has been extended by another year for the second time, despite him previously announcing his intention to step down, underlining just how difficult it is to appoint a new secretary general.

The next NATO chief will now likely be appointed in 2024, when European elections will trigger a re-shuffling of the EU’s top jobs.

This could further complicate the political balancing act of appointing a successor.

Many European leaders are rumoured to be in line for the role, including EU Commission President Ursula von der Leyen. But conflicting political interests and personal preferences mean that selecting the next NATO chief will test the alliance’s ability to compromise.

A politically-fraught decision

The role of NATO chief is appointed through informal diplomatic discussions between member states and has historically been held by a European. The military chief, the Supreme Allied Commander Europe, has always been an American.

As the war on European soil wages on, the role carries significant responsibility and political weight.

“The search for a new secretary general is not a competitive process, it is a political process,” according to Bruno Lété, senior fellow at the German Marshall Fund.

“A whole range of interests from member states must be taken into account. And member states are battling each other in the diplomatic corridors to get their candidate preferences on the front stage.”

“His [Stoltenberg’s] extended mandate likely tells us that NATO was not united internally on who could become the next secretary general. And this disunity is something to worry about,” he added.

French President Emmanuel Macron is reportedly reluctant to accept a non-EU candidate. He would rely on the new NATO chief to fulfill his vision of ‘strategic autonomy’, an EU that is less dependent on the US for its military security.

Balancing transatlantic interests will be critical.

Washington’s seal of approval

While the role is decided upon consensus, Washington’s approval is pivotal. Any candidate must be endorsed by the US President.

Mooted by Prime Minister Rishi Sunak, the candidacy of British Defence Secretary Ben Wallace was reportedly blocked by President Biden after the UK announced plans to train Ukrainian pilots on American-made F-16 jets without consultation with the US.

Wallace was also previously a soldier in Northern Ireland during the Troubles, an issue close to Joe Biden’s heart given his Irish descent.

Recent reports suggest Biden favours European Commission President Ursula von der Leyen. A former German defence minister, she would bring relevant experience and a track record on securing unanimous support for Ukraine.

The 2024 European elections will take place months before Stoltenberg’s term is due to end. If von der Leyen decides not to run for the Commission’s top job or fails to secure majority support in the European Parliament, she could emerge as the natural replacement.

But according to Lété, some NATO member states have expressed strong opposition to von der Leyen due to her previous performance as defence minister.

Breaking the glass ceiling

Von der Leyen would also tick an extra box for member states calling for the alliance to name a female successor.

Other women leaders tipped to replace Stoltenberg have seemingly failed to convince leaders. In June, Danish Prime Minister Mette Frederiksen was grilled in what seemed like a job interview by Biden and the head of the CIA during a trip to Washington. 

Denmark is seen as a strong advocate for NATO’s support to Ukraine without the political baggage of countries lying on the Eastern flank. But the country’s military budget, at 1.38% of GDP, is well below NATO’s 2% threshold.

Lithuanian Prime Minister Ingrida Šimonytė and Estonian Prime Minister Kaja Kallas are also rumoured contenders.

But a leader from an Eastern state could risk flaring up tensions with Russia. Kallas is an outspoken critic of the Kremlin who has repeatedly pushed Brussels to impose harsher sanctions on Russia. A Lithuanian appointment could also put China-NATO relations under further strain, given Šimonytė’s government’s hawkish stance on Beijing.

Calm, cool, consistent

Stoltenberg leaves a high bar when it comes to cool-headed leadership in times of crisis.

A former UN climate envoy and prime minister of Norway, he is a seasoned diplomat and experienced mediator. He was also an anti-war activist in his youth, and has admitted to hurling stones at the US Embassy in protest against the Vietnam war in the 1970s.

He has successfully kept the alliance united during one of the greatest security threats in its history, despite diverging views on the extent of the alliance’s support to Ukraine.

“NATO badly needs his experience,” said Lété.

Before the invasion of Ukraine, he also dealt successfully with rebellion within his alliance, from Donald Trump’s threats to pull out to Macron accusing the alliance of “brain death”.

He must now carefully navigate resistance within his alliance to ensure the ratification of Sweden’s accession.

Whilst no discussions on a potential successor will take place at the Vilnius summit, leaders will undoubtedly be on the lookout for a candidate that can uphold the alliance’s unity during times of war.

Asked in February what advice he would give his successor, Stoltenberg replied: “To keep Europe and North America together.”