Three years after the Bush administration authorized the first military tribunal system since the end of World War II, in order to try terrorism suspects, the proceedings will begin on Tuesday at the United States naval base here. Four defendants, who have been in a military prison here for most of that time, will be brought in shackles into a highly secure courtroom while their lawyers argue over preliminary motions for trials that will probably not begin for several months. United States officials are keenly aware that Guantánamo, which has served as a prison for as many as 800 detainees captured at the end of the Afghanistan war, has become in many parts of the world a symbol of American high-handedness and unwillingness to acknowledge international law. Last month, Lord Goldsmith, the attorney general of Britain, told a law conference in London that the tribunals did not offer enough guarantees of a fair trial. About OODA Analyst