Mr. Trump’s persistent and sometimes volatile effort to bring a diplomatic end to the war between Ukraine and Russia has forged stronger bonds among European leaders.

Allied talk of sending European peacekeeping forces to protect Ukraine as part of a possible peace deal with Russia has sparked a backlash in Germany, a country still scarred by its militaristic Nazi...

"We cannot agree with the fact that now it is proposed to resolve questions of security, collective security, without the Russian Federation. This will not work," Lavrov said.