Chinese leader Xi Jinping’s meetings in Moscow with Russian President Vladimir Putin puts Washington in an uncomfortable position: on the sidelines as two adversaries discuss a Ukraine peace proposal that the U.S. has deemed unacceptable.

U.S. officials have publicly expressed deep skepticism about the Chinese idea, saying its call for a cease-fire would reward Moscow’s invasion by cementing its territorial gains. Privately, though, the meetings and the proposal have provoked a sense of unease within the administration of U.S. President Joe Biden, leading in turn to questions about the broader U.S. approach to the two countries.

According to one administration official, who asked not to be identified discussing internal deliberations, the U.S. is worried about being backed into a corner over the Chinese proposal. Regardless of the U.S. reservations, dismissing it outright could let China argue to other nations that are weary of the war — and of the economic damage it’s wreaking — that Washington isn’t interested in peace.