Former U.S. Deputy Secretary of State Richard Armitage, a towering figure in the world of U.S.-Asian diplomacy known for his close connections to Japan, has died at the age of 79.

Armitage, who served in the State Department’s No. 2 post in the administration of former U.S. President George W. Bush, died of a pulmonary embolism on Sunday, his consulting firm said in a statement released Monday.