Photo: The Canadian Press

Former South Korean presidents Roh Tae-woo, left, and Chun Doo-hwan appear in court in 1996.

Former South Korean President Roh Tae-woo, a major player in a 1979 coup who later became president in a landmark democratic election before ending his tumultuous political career in prison, died on Tuesday. He was 88.

The Seoul National University Hospital said Roh died while being treated for an illness. It gave no further details or his cause of death. Roh, who ruled South Korea as president from 1988-1993, was known to have suffered many health problems including cerebellar atrophy for years.

Roh was a key participant in the December 1979 military coup that made his army friend and coup leader Chun Doo-hwan president after their mentor, dictator Park Chung-hee, was assassinated following 18 years of rule.

Roh led his army division into Seoul and joined other military leaders for operations to seize the capital. The coup — and a subsequent crackdown by the Chun-controlled military on pro-democracy protesters in the southern city of Gwangju in 1980 — are two of the darkest chapters in South Korea’s turbulent modern history. About 200 people were killed in the military-led crackdown in Gwangju, according to government records.

Roh was Chun’s hand-picked successor, which would have assured him the presidency in an easy indirect election. But a massive pro-democracy uprising in 1987 forced Roh and Chun to accept a direct presidential election that was regarded as the start of South Korea’s transition to democracy.

Despite his military background, Roh built a moderate and genial image during the campaign, calling himself an “average person.” He eventually won the hotly contested election in December 1987, largely thanks to a split in liberal votes between opposition candidates Kim Young-sam and Kim Dae-jung, who both later became presidents.

During his five-year term, Roh aggressively pursued ties with communist nations under his “Northward Diplomacy” as communism fell in Eastern Europe and the Soviet Union dissolved.

South Korea was then deeply anti-communist because of its rivalry with North Korea, but under Roh it opened diplomatic relations with a communist nation for the first time — Hungary in 1989, the year when the Berlin Wall fell and communism crumbled across Eastern Europe.

Roh’s government established relations with the Soviet Union in 1990 and with China in 1992. Relations with North Korea improved under Roh, with the two sides holding their first-ever prime ministers’ talks, adopting a landmark joint statement on denuclearization of the Korean Peninsula and joining the United Nations at the same time.

Earlier, Roh oversaw the hosting of the 1988 Summer Games in Seoul, the final Olympics of the Cold War era that showed how South Korea had rebuilt itself from the ashes of the 1950-53 Korean War. North Korea boycotted the 1988 games.

Ties between the two Koreas have since suffered ups and downs. Despite numerous denuclearization pledges — including one made during Roh’s presidency — North Korea still maintains its nuclear weapons program which it views as a means of survival.

On domestic politics, Roh was seen by many as lacking charismatic and aggressive leadership. His nickname, “Mul (Water) Tae-woo,” implied his administration had no color and no taste. He still brought more openness by allowing more political criticism, in contrast with his authoritarian predecessors, Park and Chun. The governments led by Park and Chun often used security laws to suppress political opponents and restrict speech under the pretext of guarding against civil disorder and North Korean threats.

After his successor, Kim Young-sam, investigated the coup and military-led crackdown, Roh was arrested, convicted of mutiny, treason and corruption and received a 22-year and six-month prison term. Chun was sentenced to death.

The Supreme Court reduced those sentences to life imprisonment for Chun and 17 years for Roh. After spending about two years in prison, both Roh and Chun were released in late 1997 under a special pardon requested by then president-elect Kim Dae-jung, who sought national reconciliation amid an Asian financial crisis.

Roh had stayed mostly out of the public eye following his release from prison, refraining from political activities and speeches. In recent years, he suffered prostate cancer, asthma, cerebellar atrophy and other health problems.