Vietnamese President Trần Đại Quang died Sept. 21 from an undisclosed "serious illness" triggered by a "rare virus," according to state-run media.

This former Minister of Public Security (MPS) from 2011 to 2016 was the eighth president of the Socialist Republic of Vietnam and the country's second most powerful politician. He became president in April 2016. Quang joined the Communist Party of Vietnam in 1980.

His position as president and head of state, however, was largely ceremonial and a far cry from the absolute power he enjoyed as MPS chief. It generally involved meeting visiting leaders and hosting diplomatic events.

Quang, 61, had sought treatment in Japan for over a year before his death. He was rushed to the 108 Military Hospital in Hanoi on the afternoon of Sept. 20. He died from a "rare virus," said Nguyen Quoc Trieu, who is in charge of the health care committee for top communist leaders. This rare virus was not identified, however.

Despite representing his country's interest against China in the South China Sea dispute, Quang was praised by China as "an outstanding leader ... (who) made important contributions to the national development of reform and opening up in Vietnam."

Quang earned notoriety as a hardliner, having spent most of his career at the shadowy MPS. He joined this ministry in 1975 and rose through the ranks in this secret society that controls Vietnam's secret police and intelligence apparatus.

Quang did not appear in public for more than a month in 2017, raising rumors about his health. He hosted president Donald Trump during his first state visit to Vietnam in 2017 where Trump attended a summit of Pacific Rim leaders.

Quang's last public appearance was at a Politburo meeting of the Communist Party and a reception for a Chinese delegation on Sept. 19. He looked frail on a state-run television broadcast. His death won't lead to any major changes in the political leadership or in the communist party, said Western analysts.

United Nations Secretary-General Antonio Guterres praised Quang as "an important promoter of Vietnam's development," saying he was "saddened to learn of the death" of Quang who "will be long remembered in his country and beyond."

Quang was born Oct 12, 1956, in Ninh Binh province. He joined the police academy and went to college at the College of Foreign Language in Hanoi. Quang is survived by his wife and two sons.