Truong was arrested in January 1978, and a search of his apartment revealed two Top Secret State Department documents in his possession. The documents had been provided to him by Humphrey, a
United States Information Agency employee, to be passed on by Truong to Vietnam via a woman who turned out to be a
double agent for the
CIA and the
FBI. The spy ring routed purloined classified information through Vietnam's
United Nations mission in New York and its French Embassy in Paris. In retaliation, the American government, which lacked formal diplomatic relations with Vietnam at the time, expelled
Đinh Bá Thi, Vietnam's UN legate, from the United States. The ambassador had been named an unindicted co-conspirator when Truong and his accomplice,
United States Information Agency employee
Ronald Humphrey, were indicted. In 1978, Truong was tried with co-conspirator Humphrey. Charged with six counts, including conspiracy, espionage, theft of classified information and failing to register as agents of a foreign government. Humphrey's defense was that he was trying to purchase the release of his common-law wife and her four children from Vietnam. Truong and Humphrey were convicted of spying for Vietnam and both were given a 15-year prison sentence. It is the only case of military espionage to come out of the
Vietnam War. The case involved passing on documents through the wife of a naval attache,
Yung Krall, codenamed "Agent Keyseat". ==References==