A US defense official said late Friday that Russia has fired more than 1,080 missiles since the start of its military operation in Ukraine.
"We assess the airspace over Ukraine remains contested. The Ukrainian Air Force is continuing to fly aircraft and employ air and missile defense," the official said in a background statement.
Russia remains largely stalled across the country in day 23 of its operation, he said.
"Near Kyiv, we still observe Russian forces have not made significant advances toward the city in the north/north west. And to the east of Kyiv, we have observed no movement of Russian forces. They remain approximately 30 km (19 miles) to the east," said the official, adding that the Russian army is facing heavy resistance from Ukrainians.
The official noted that Chernihiv in northern Ukraine remains isolated but Ukrainians are defending the city and in the vicinity of northeastern Kharkiv province, Russian forces appear to have made no apparent progress on the ground.
The official said Ukrainians continue to defend Mykolaiv near the Black Sea in southern Ukraine.
Russian forces still appear to remain outside the city to the northeast, according to the official.
"Mariupol city in southeastern Ukraine remains isolated, with Russian forces north and east of the city. We continue to see heavy bombardment there. Ukrainians are defending the city," he said.