BRUSSELS — As Mark Rutte takes the reins at NATO, the defense pact is confronting challenges new and old – but is the former Dutch Prime Minister well-placed to meet them?

The 57-year-old, one of Europe’s longest-serving democratic leaders, will have to face up to a belligerent Russia, fractious EU relations, and the potentially existential threat from a Donald Trump White House, defense experts have told Euronews.

Rutte, a history graduate, has since 2010 presided over four different governments in the Netherlands — but resigned in July after his four-party coalition fell apart over how to curb migration.

As of Tuesday (1 October), he’ll take over as Secretary-General of the 32-nation NATO alliance, as former Norwegian Prime Minister Jens Stoltenberg steps down – and Rutte’s career history could make him uniquely well-placed.

Rutte takes office just a month before the US goes to the polls to decide whether Donald Trump or Kamala Harris will lead NATO’s biggest member.

That’s sent alarm bells ringing, given Trump has proved lukewarm about support for Ukraine, and about the transatlantic security pact more generally.

There’s still plenty that’s unknown about what a second Trump administration might mean for the North Atlantic pact, analyst Sophia Besch told Euronews.

But if Washington calls for a “much, much smaller NATO, then it does become existential”, said Besch, who’s a fellow at the Carnegie Endowment for International Peace — and she reckons there are ways of minimizing that risk.

She points to recent debates during the presidential campaign where Trump claimed credit for persuading other NATO members to spend more on their militaries, suggesting that Europeans can assuage his fears.

“That’s probably going to be the approach ... frame it in a way that European defense efforts are a response to US pressure,” Besch said.

If buttering up Trump is a requirement for the role, so much the better for Rutte, who “who was able to establish a good working relationship with him when he was Dutch prime minister,” former NATO spokesperson Oana Lungescu told Euronews.

Rutte’s seen as a down-to-earth leader, often pictured riding his bicycle around his hometown of The Hague, or crunching an apple as he walks to a meeting from his prime ministerial office.

But his friendly-but-tough approach with Trump could “stand him and NATO in good stead” if the Republican wins in November, added Lungescu, who is now a Distinguished Fellow at think tank the Royal United Services Institute.

Whoever’s in the White House, both Besch and Lungescu agree Europe must step up defense spending given Russian aggression.

Rutte himself has been a “very strong supporter” of Ukraine, Lungescu said, citing fighter jets, ammunition and security guarantees provided by the Netherlands under his tenure.

Yet perhaps the trickiest relationship Rutte must navigate is not Washington or Kyiv, but another international organization based in Brussels – the European Union.

European Commission President Ursula von der Leyen’s recent announcement she was appointing a defense commissioner, Lithuania’s Andrius Kubilius, prompted a furious reaction from Stoltenberg, worried she was moving in on his patch.

“What EU should not do is to start to build alternative defense structures,” Stoltenberg told reporters, adding: “Countries can only have one set of capability targets, they cannot have two, and that's NATO's responsibility.”

Rutte’s challenge will be to rebuild a relationship with the EU which, in Besch’s words, “can’t get much worse ... he has his work cut out for him.”

“This idea that this [EU defense commissioner] is somehow an affront to NATO just shows that the EU hasn’t been successful in making its own case,” Besch said.

Lungescu, who worked with Stoltenberg for almost a decade, is more upbeat, saying cooperation has reached “unprecedented levels”, and that Stoltenberg and von der Leyen had “very good chemistry” — though she agrees there’ll be “confusion” if the EU duplicates NATO structures or standards.

But, Lungescu adds, “there are some who perhaps trusted Stoltenberg a bit less because his country is not in the EU” — an issue that European Council veteran Rutte is well placed to rectify.

Both Besch and Lungescu talk of new threats from China, whose flexing of military muscles is increasingly irking the US.

But Rutte’s greatest challenge will perhaps be NATO’s oldest: Russia.

“Deterrence and defense is at the heart of NATO today and will remain at the heart of NATO for the foreseeable future,” Lungescu said, adding: “This is a dangerous world, which is not getting any less dangerous.” — Euronews