Russia on Sunday rescinded earlier pledges to pull tens of thousands of its troops back from Ukraine’s northern border, a move that U.S. leaders said put Russia another step closer to what they said was the planned invasion of Ukraine. Residents of Ukraine’s capital filled a gold-domed cathedral to pray for peace.

Russia’s action extends what it said were military exercises, originally set to end Sunday, that brought an estimated 30,000 Russian forces to Belarus, Ukraine’s neighbor to the north. They are among at least 150,000 Russian troops now deployed outside Ukraine’s borders, along with tanks, warplanes, artillery and other war materiel.