Tokio Tobita, a former sergeant in the Imperial Japanese Army who spent 10 years in prison for war crimes, met one of his American guards on Thursday in an emotional reunion made possible by an exhibition of war prison art.

"I'm speechless. The only thing I can say is I'm really moved," Tobita said after his reunion with Buck Langdon, a former U.S. soldier who served as a guard at Tokyo's Sugamo Prison.

"Never in my life had I thought something like this would happen," said Tobita, who was visiting the United States for the first time, accompanied by two sons.

Tobita, 84, and Langdon, 73, were in Philadelphia for a special exhibition at the Philadelphia Art Alliance gallery on art produced by Japanese prisoners who spent time at Sugamo for war crimes committed during World War II.