Nobuo Matsunaga, who served as Japan's ambassador to the United States in the 1980s, has died of heart failure, government officials said Wednesday. He was 88.

Matsunaga, who joined the Foreign Ministry in 1946, died at a Tokyo hospital Dec. 1. He held many senior posts, including vice minister for foreign affairs and ambassador to Mexico, until his retirement from the ministry in 1989. He became the head of the Japan Institute of International Affairs in 1990.