Former U.S. President George W. Bush says that when he was in office, he warned China that the U.S. would review the launch of a military attack on North Korea if the nuclear problem in the North was not resolved diplomatically.

Bush said in his recently released autobiography “Decision Points” that he made the warning to then Chinese President Jiang Zemin in February of 2003.

The former U.S. president said that he asked Jiang to form a united front against North Korea after gaining intelligence on Pyongyang’s nuclear ambitions. But the Chinese president reportedly rejected the request, saying that exercising influence on North Korea was a very complex matter.

Bush said in the autobiography that he believes North Korea test-fired a long-range missile in July of 2006 as a way of drawing international attention.