TOKYO —  A new top-of-the-line U.S. guided missile destroyer with missile-tracking radar was deployed to Japan on Saturday, as tensions mounted over neighboring North Korea's recent missile tests.

The USS Mustin arrived Saturday at Yokosuka, homeport to the U.S. Navy's 7th Fleet, with its crew of 300 sailors for permanent assignment to the region, said 7th Fleet spokeswoman Hanako Tomizuka.

The move comes as the United States restructures its regional defenses amid growing concern about the nuclear ambitions of North Korea, which stunned northeastern Asia on Wednesday by test-firing seven missiles.

In August, Yokosuka will also welcome the USS Shiloh, which last month demonstrated its ability to shoot down missile warheads in a landmark test off the coast of Hawaii.

The Mustin, commissioned in 2003, is one of the most advanced in the fleet, but its deployment to Yokosuka was previously planned and not made in response to North Korea's latest missile shots, Tomizuka said.

Both the Mustin and the Shiloh are equipped with radar systems that employ so-called Aegis technology that is geared toward tracking and shooting down enemy missiles. The system was instrumental in identifying and assessing Wednesday's missile launchings, which all fell apparently harmlessly into the Sea of Japan.

The U.S. Navy now has eight Aegis-equipped vessels at Yokosuka, Kyodo News agency reported.