Russian President Vladimir Putin has called on Ukrainian troops in the Russian region of Kursk to surrender, as diplomatic back-and-forth continues over a potential US-brokered ceasefire with Ukraine.

President Trump and President Vladimir V. Putin both claimed that Ukrainian forces were surrounded. Ukraine’s top military commander vowed to “hold the line.”

Vladimir Putin said Ukraine must surrender after President Donald Trump urged the Russian leader to spare the lives of Ukrainian soldiers, following ceasefire talks between the U.S. and Russia in Moscow.