ALEXANDRIA, Virginia (Reuters) - The U.S. government knew by the 1990s how al Qaeda trained suicide operatives but missed capturing the man who masterminded the September 11 attacks about four years before they occurred, an FBI agent said on Tuesday. FBI agent Michael Anticev said in testimony at a sentencing trial for September 11 conspirator Zacarias Moussaoui that the U.S. government knew by the mid 1990s that there were several al Qaeda training camps in Afghanistan and other countries. Operatives at the training camps were taught how to carry out terrorist operations, including suicide missions, and were trained in how...