Washington ? James R. Lilley, a longtime CIA operative and later the U.S. ambassador to China during the time of the Tiananmen Square crackdown, has died. He was 81.

The Washington Post said Lilley, who was born in China to an oilman father and schoolteacher mother, died Thursday in Washington from complications related to prostate cancer.

Lilley had a close relationship with former President George H.W. Bush dating to the early 1970s, when Lilley headed the CIA’s operations in Beijing and Bush was the chief of the U.S. mission there. During the 1989 Tiananmen protests, Lilley, a stern critic of the crackdown, often sent his reports about the unfolding events directly to Bush, who was then president.

In a statement Friday, Bush called Lilley “a most knowledgeable and effective ambassador who served with great honor and distinction.”