A former Red Army Faction fugitive sentenced to 12 years in prison for a 1970 hijacking has filed an appeal with the Supreme Court, claiming the sentence is too severe, a source said Thursday.

Lawyers for Yoshimi Tanaka, 54, filed the appeal against an April 30 Tokyo High Court ruling that upheld the sentence handed down by the Tokyo District Court in February 2002, the source said.

The lawyers said the 12-year term is too harsh for what Tanaka did, but the high court presiding judge, Shogo Takahashi, said in upholding the earlier ruling that the hijacking was “an extremely heinous crime aimed at ruining democracy and social order.”

Tanaka and eight other Red Army Faction members hijacked a Japan Airlines Boeing 727 on March 31, 1970, after it left Tokyo bound for Fukuoka, and forced it fly to Pyongyang.

The plane landed at an airport outside Pyongyang on April 3 and the skyjackers were granted political asylum by North Korea. En route, they inflicted minor injuries on five of the 129 passengers and crew members aboard.

Tanaka was also convicted of other charges, including throwing a Molotov cocktail at a police station in Tokyo in 1969.

After resurfacing in Cambodia in March 1996, he was arrested and handed over to Thai authorities on suspicion of passing counterfeit U.S. currency in Thailand. He was later acquitted there, and Thailand extradited him to Japan in June 2000.