Prime Minister Yukio Hatoyama gave up on a bedrock campaign pledge and accepted a longstanding U.S. proposal for positioning American troops in Japan, backing down from a battle with Washington as the two nations grapple with North Korea's aggression and China's rising power in the region.

The move hands the Obama administration an important foreign-policy victory, allowing Washington to avoid what, for a time, appeared to be an unwelcome need to rearrange its regional defense strategy in North Asia while fighting two wars...