By Phil Stewart TOKYO (Reuters) - The United States will deploy two additional destroyers equipped with missile defense systems to Japan by 2017, in a move Defense Secretary Chuck Hagel said on Sunday was a response in part to North Korean missile launches that have alarmed the region. Tensions have been building between North Korea and its neighbors since Pyongyang - in an apparent show of defiance - fired two Rodong missiles on March 26, just as the leaders of Japan, South Korea and the United States were sitting down to discuss containing the North Korean nuclear threat.