Kyiv is now entirely surrounded and civilians can no longer evacuate, the mayor of Kyiv, Vitali Klitschko, said Sunday. “We can’t do that, because all ways are blocked,” he said. “Right now we are encircled.” A spokesperson for the mayor later told The Kyiv Independent that Ukrainians are still ready to fight and that Klitschko misspoke.

The news comes just hours after a senior U.S. defense official said Russian forces were 30 kilometers away from the city. Ukrainians have been taking up arms in Kyiv following days of explosions, with combat breaking out in the streets. Earlier Sunday, Russian President Vladimir Putin announced a plan to put his nuclear forces on high alert. Government officials in the U.K. have warned that Putin has hatched a plot to install a pro-Kremlin regime in Ukraine as part of his invasion plans. The U.S. government is aware of similar plots, a senior U.S. State Department official said.