"U.S. relations with the Kingdom of Cambodia have become increasingly strained in recent years in light of Prime Minister Hun Sen's suppression of the political opposition and his growing embrace of the People's Republic of China (PRC). During the previous decade, U.S. engagement with the Kingdom slowly strengthened as western countries continued to pressure Hun Sen to abide by democratic norms and institutions and as the U.S. government attempted to prevent Cambodia from falling too heavily under China's influence. Following strong performances by the opposition in the 2013 and 2017 elections, the Cambodian government banned the largest opposition party, the Cambodia National Rescue Party (CNRP), in 2017. As a result, the ruling Cambodian People's Party (CPP) ran virtually unopposed in the 2018 National Assembly election. The Trump Administration and Congress have imposed sanctions in order to pressure Hun Sen into restoring democratic rights and dropping criminal charges against opposition leaders."
CRS Report for Congress, R44037
Congressional Research Service: https://crsreports.congress.gov