Moscow’s forces are three miles from Dnipropetrovsk, a province they have never invaded. If they cross in, the advance would be a morale blow to Ukraine and complicate any territorial negotiations.

Ukrainian service members of the 68th Jaeger Brigade named after Oleksa Dovbush attend military exercises at a training ground, amid Russia's attack on Ukraine, in Dnipropetrovsk region, Ukraine February 20,

U.S. and Russian participants have met in Switzerland for unofficial talks about the Ukraine war in recent months, including as recently as last week, three sources with knowledge of the matter said.