BRUSSELS (AP) — Secretary-General Jens Stoltenberg, one of NATO's longest-serving leaders, officially stepped down on Tuesday. In his place, former Dutch Prime Minister Mark Rutte assumes the role, guiding the military alliance through some of the most formidable challenges it has ever faced.

The two leaders, who first shared the NATO meeting table as representatives of Norway and the Netherlands 14 years ago, exchanged greetings in front of NATO’s headquarters in Brussels. Standing before the flags of the alliance’s 32 member nations, they laid wreaths in remembrance of fallen soldiers.

“Mark is perfectly suited to lead NATO,” Stoltenberg said, becoming visibly emotional as he reflected on his decade-long tenure. “Throughout his 14 years as prime minister, he’s shown an ability to lead coalition governments, refine compromises, and build consensus — essential qualities here at NATO,” he continued.

In reply, Rutte expressed his enthusiasm for the road ahead, saying, “I’m eager to get started.”

The handover ceremony continued inside the North Atlantic Council’s grand hall, the venue for key discussions between ambassadors, ministers, and leaders. As military personnel applauded, Stoltenberg helped Rutte begin his new role by ceremoniously passing him a Viking gavel for use in future NATO meetings.

Rutte outlined the central priorities that will shape his leadership: maintaining NATO’s support for Ukraine amid the ongoing conflict, boosting defense budgets, and strengthening relationships with partners worldwide, particularly in regions like Asia and the Middle East.

Rutte also stressed the importance of keeping a solid trans-Atlantic connection among the U.S., Canada, and Europe. Confident in his ability to collaborate with whoever wins the upcoming U.S. presidential election, he assured, “I know both candidates very well.”

Polls suggest that the U.S. election this coming November could be closely contested, possibly seeing a return of Donald Trump. During his previous term, Trump criticized NATO allies over their low defense spending, straining alliances and causing concern about the future of the organization's fundamental security commitments.

Some smaller NATO members feared the U.S. under Trump might abandon its key principle of collective defense — the core feature that binds the members together. Nevertheless, Rutte emphasized: “I will work effectively with either candidate, irrespective of the election's outcome."

Stoltenberg, serving from 2014, was NATO’s 13th secretary-general. His term began in a tense geopolitical landscape, as Russia covertly infiltrated Ukraine through the presence of “little green men,” and annexed Crimea. His time in office saw Europe’s massive defensive buildup in response to growing threats.

Only Joseph Luns, a Dutch diplomat, has previously held the NATO secretary-general position longer, serving for 12 years.

The overarching role of the NATO secretary-general involves coordinating the organization’s activities, managing its headquarters, and communicating on behalf of the entire 32-nation alliance. When a new leader steps in, continuity of goals remains vital.

Rutte now takes up leadership as Ukraine approaches the grim 1,000-day milestone of Russia's full-scale invasion. In his inaugural speech, Rutte emphasized, “There can be no secure Europe without a strong and independent Ukraine." Reaffirming NATO's 2008 commitment, he declared, “Ukraine’s rightful place is in NATO.”

The conflict in eastern Ukraine persists, with Russia gaining ground. Ukraine’s military maneuvers have given them a slight foothold in Russia’s Kursk region, a temporary morale booster, though Ukraine remains significantly outmatched in numbers and resources.

Rutte faces the challenge of rallying NATO countries to continue steadfast support for Ukraine. Since the invasion, the alliance's ranks have grown with the addition of Finland and Sweden, who sought NATO membership for protection against Russian aggression.

Meanwhile, Trump has been vocal in criticizing U.S. assistance to Ukraine. He recently suggested that Ukraine’s President Volodymyr Zelenskyy should have negotiated with Russian President Vladimir Putin before Russia commenced its 2022 invasion.

Despite a long-held desire by Ukraine to join NATO, certain member nations, including the U.S. and Germany, caution against allowing Ukraine into the alliance while actively engaged in war.