North Korea announced plans last month to launch what it says is a communications satellite from its Musudan-ri launch site between April 4-8. However, the U.S., Japan and South Korea believe that the secretive state is planning to test its Taepodong-2 long-range missile.
Following North Korea's announcement Japan's Security Council on Friday gave approval to the defense ministry to destroy the North Korean rocket if Pyongyang goes ahead with the launch.
The Kyodo news agency reported that the Kongou and Choukai warships, fitted with Standard Missile-3 ballistic interceptor missiles, had set sail from the Sasebo base on Saturday.
Four Patriot guided-missile units will also be deployed on the ground in the prefectures of Akita and Iwate, as well as around the capital, including the Defense Ministry headquarters near the Imperial Palace.
"It's important to deal with and eliminate the North Korean projectile should it threaten the people's security and safety by falling into our airspace, waters or soil," the Kyodo news agency quoted Japanese Defense Minister Yasukazu Hamada as saying on Friday.
A third Aegis destroyer the Kirishima, which is expected to track the missile, has also set sail from its Yokosuka base in the Kanagawa Prefecture en route to the Pacific Ocean.
Russia also announced that its early warning system will be put on high alert in connection with the launch, the head of a Russian think tank said on Friday.
"All of our missile attack early warning stations monitoring the eastern sector will be put on high alert ahead of the Korean satellite launch," Anatoly Tsyganok, head of the Center for Military Forecasts at the Institute of Political and Military Studies, said earlier.