President Donald Trump -- clearly frustrated by the failure of his diplomatic efforts to date -- has raised the prospect of entirely abandoning American engagement.

Russia launched one of its largest air strikes on Kyiv in over three years of war and struck a maternity ward in the southern city of Odesa, officials said.

"We extend deepest condolences to the victims' families. This senseless attack runs counter to President Trump's call to stop the killing and end the war," the U.S. Embassy in Ukraine said in a statement.