The United States will not provide the F-16 fighter jets that Ukraine has sought in its battle against Russia, U.S. President Joe Biden said, as Russian forces claimed a series of incremental gains in the country's east.

Biden said the U.S. wouldn't provide the jets when asked by reporters at the White House on Monday.

Ukraine planned to push for Western fourth-generation fighter jets such as the F-16 after securing supplies of main battle tanks last week, an adviser to Ukraine's defense minister said on Friday.