The U.S. said it will impose sanctions on the breakaway regions, but not for now on Russia.

White House officials said on Monday that President Biden will impose economic sanctions on the two separatist regions of Ukraine that President Vladimir V. Putin recognized as independent, but stopped short of imposing any penalties directly on Russia.

The limited nature of the sanctions appeared intended to allow the United States and its European allies to hold in reserve the more aggressive sanctions they have threatened to impose on Moscow if Mr. Putin sends Russian armed forces into Ukraine, and to allow for the increasingly slim possibility of a diplomatic solution.