Japan and Washington have agreed to strengthen cooperation on missile defense amid concerns of a possible long-range rocket launch by North Korea, as US forces wrapped up massive Pacific war games in a show of military might. The five days of exercises - the largest in the Pacific since the Vietnam War - brought together three aircraft carriers along with 22,000 troops and 280 warplanes off the island of Guam in the western Pacific. The exercise "was a demonstration of the US Pacific Command's ability to quickly amass a force ... and project peace, power and presence in the region," Air Force Lt. Gen. David Deptula told The Associated Press. The US will launch similar war games with seven other countries off Hawaii next week. The monthlong exercises, known as RIMPAC, will bring together forces from Australia, Canada, Chile, Peru, Japan, South Korea, Britain and the US.