Pol Pot retreated into Thailand with the remnants of his Khmer Rouge army and began a guerrilla war against a succession of Cambodian governments lasting over the next 17 years. After a series of internal power struggles in the 1990s, he finally lost control of the Khmer Rouge. In April 1998, 73-year-old Pol Pot died of an apparent heart attack following his arrest, before he could be brought to trial by an international tribunal for the events of 1975-79.