The EU's predecessor, the European Coal and Steel Community, opened its first mission in London in 1955, after three years non-EU countries began to accredit their missions in Brussels to the Community. The US had been a fervent supporter of the ECSC's efforts from the beginning, and Secretary of State Dean Acheson sent Jean Monnet a dispatch in the name of President Truman confirming full US diplomatic recognition of the ECSC. A US ambassador to the ECSC was accredited soon thereafter, and he headed the second overseas mission to establish diplomatic relations with the Community institutions.[1]