The new Trump foreign policy team has brought a dizzying message to European allies on A.I., Ukraine and more. It has already left many angered and chagrined.

President Volodymyr Zelensky of Ukraine and European defense ministers had expressed concern that they might not be present for talks between President Trump and Russia’s leader to end the war.

In his first trip abroad, the new U.S. defense secretary told Ukrainian and NATO officials that a durable peace could only come ‘with a realistic assessment of the battlefield.’

Deterring Russia from re-invading Ukraine, once this war ends, could require 150,000 troops and American help with air cover, intelligence and missile defense, experts say.

European leaders will gather Monday to plot a rough path forward on defense. Wavering support from President Trump is likely to drive the debate.

President Trump jabs at the Russian leader with threats; Vladimir Putin responds with flattery. But there are notable signals in their jousting, including a revived discussion about nuclear arms control.

Jake Sullivan, the national security adviser, said in an interview that “we’ve just stuck with our theory, which is managed competition.” Trump and Xi Jinping might have other plans.

Senator Marco Rubio, who is nominated for secretary of state, has a long history of personal and policy differences with President-elect Donald Trump.

The White House scrambled to get a message to President Vladimir V. Putin of Russia last year after U.S. intelligence agencies said a Russian military unit was preparing to send explosive packages on cargo planes.

The president argued in a speech that he strengthened U.S. alliances during his four years in office and that America’s adversaries are weaker than when he took over.

In an impassioned address to officials from countries supporting Ukraine, Mr. Zelensky said “a new chapter” would be starting for Europe and the rest of the world, requiring even more cooperation.

In an hourlong news conference at his Florida club, Mar-a-Lago, the president-elect delivered a hodgepodge of grievances, complaints and false claims.

At the end of a tenure marked by war and division, the outgoing secretary of state defends his legacy on Gaza and Ukraine and says he’s made America stronger.

Russia has assembled a fleet of hundreds of vessels to covertly ship its oil. With so many ships at sea, the idea of using some to cause havoc may be proving irresistible to the Kremlin.

Finland seized an oil tanker that authorities believe might have deliberately cut vital undersea cables. Finnish authorities believe the tanker may be linked to Russia.