A senior U.S. diplomat visited Bolivia on Wednesday in an effort to repair badly strained relations between the two countries. Undersecretary of State for Latin America Thomas Shannon said upon his arrival at the airport in La Paz that the goal of his trip was to improve the contentious tone of the bilateral dialogue. Relations between the United States and Bolivia have been poor since President Evo Morales took office three years ago. He frequently accuses the United States of siding with his political opponents. Last year, the White House expelled Bolivia's ambassador to the United States in retaliation for Bolivia's expulsion of the U.S. ambassador and U.S. Drug Enforcement Agency agents.