Honduras is indefinitely postponing the accreditation of the U.S. ambassador.
President Manuel Zelaya says Honduras is not breaking relations with the United States, but is supporting Venezuela and Bolivia.
Bolivian President Evo Morales has expelled the U.S. ambassador there, accusing him of inciting violent protests.
Venezuelan President Hugo Chavez has followed suit, and U.S. officials are responding by kicking out the Bolivian and Venezuelan ambassadors.
Violent clashes over Bolivia's future have claimed eight lives and unleashed the diplomatic crisis, as South American allies demanded that Washington stay out of their affairs.
Zelaya made the announcement Friday.