The U.S. government covertly expelled two Chinese Embassy officials after they drove onto a sensitive military base in Virginia, according to the The New York Times. The incident, which has been kept secret since it happened in September, marks the first time Chinese diplomats have been suspected of espionage in the U.S. in more than 30 years. The Times reports that the officials drove onto a Virginia military base with their wives in September and evaded military personnel who tried to deter them. A fire truck eventually had to be used to block their path. At least one of the officials is thought to be a Chinese intelligence officer. The Times says that Chinese officials with diplomatic passports have recently shown up unannounced at government research facilities in what is thought to be an increased effort to spy on the U.S. The last time the U.S. is known to have expelled Chinese diplomats was in 1987.