Several other nation representatives also walked out of a trade ministers meeting in Bangkok.
Representatives from Canada, New Zealand, Japan and Australia joined the Americans, led by Trade Representative Katherine Tai, in walking out of the APEC meeting.
Meanwhile, Russia has stopped delivering gas to Finland in an escalation of a dispute over energy payments with Western nations.
Russia earlier claimed victory in the battle for Mariupol's Azovstal steel plant which has been under siege for almost three months.
Moscow says the remaining Ukrainian soldiers there have surrendered, including more than 500 yesterday.
The Kremlin's focusing on trying to capture the Donbas region, in the east.