tricking him into accepting north korea's recent missile tests. the torrent of north korea short range missile tests, ten launches over just one month, tonight are finally taking a toll. according to reuters, japan's defense minister now says his government believes kim jong un's missiles and warheads are declined to penetrate japan's ballistic missile shield. >> these are the kinds of things that gives north korea a bit more of a complication to japan's defense job. >> reporter: a u.s. official tells cnn the u.s. assessment is that north korea is working on missiles that have new maneuvering capabilities, but japan and the u.s. have the ability to deal with them. both countries have destroyers in the sea of japan which have intercepter missiles designed to shoot down some of north korea's missiles and warheads. analysts say japan plans to deploy two new land based missile sites that could shoot down north korean rockets. the north koreans are working on a missile that could evade current defenses.