Washington and Tokyo agreed today to keep a contentious U.S. Marine base on the Japanese island of Okinawa, reaffirming the importance of their security alliance and the need to maintain American troops in the country.

In a statement, the two allies agreed to move the Marine Corps Air Station Futenma to Henoko, a less crowded part of the southern island. The decision is broadly in line with a 2006 deal, but represents a major broken campaign promise on the part of Japanese Prime Minister Yukio Hatoyama.

Hatoyama came to office in September promising to move the Marine base off the island. But after months of discussions with Washington and Okinawan officials, the prime minister said the base needed to stay in Okinawa.

His decision has angered residents who complain about base-related noise, pollution and crime.