Bulgaria has proven to be an effective partner to the United States in joint efforts to clamp down on drug trafficking, money laundering, human trafficking and to increase border protection, David Johnson, assistant secretary for the bureau of international narcotics and law enforcement affairs and deputy secretary of state, said in a letter to Bulgarian Prime Minister Boyko Borissov on August 23 2010.Borissov met Johnson in Sofia at the beginning of June 2010, after which Johnson vowed to send experts to assist with institutional reforms.Johnson expressed his gratitude for Bulgaria's efforts regarding legal reforms aimed at improving transparency in the judicial system, the Government said in a media statement.