Japanese Maritime Defence Force's Aegis cruiser Myoko and Kongo leave the Sasebo naval base in Nagasaki prefecture.
TOKYO: Japan has issued an order to shoot down a North Korean rocket if it threatens the nation's territory, a government official says.
Tokyo has readied surface-to-air missiles in and around Tokyo, as well as in Okinawa, and is putting its armed forces on standby ahead of Pyongyang's planned missile launch.
It is also deploying Aegis warships in neighbouring waters.
South Korean protesters at a rally denouncing North Korea's rocket launch. Photo: AP
The Defence Minister, Satoshi Morimoto, has told forces to destroy the projectile or any parts that look set to fall on Japanese territory, the Chief Cabinet Secretary, Osamu Fujimura, told reporters on Friday.
The communist North announced last week a December 10 to 22 window, its second long-range rocket launch this year after a much-hyped but botched attempt in April.
Pyongyang insists it is a peaceful satellite launch, but the international community sees it as a poorly disguised test of ballistic missile technology, which is banned under United Nations Security Council resolutions.
Washington and Seoul have urged Pyongyang to scrap the launch while Tokyo has postponed talks originally planned this week with North Korea.
Once Pyongyang launches the rocket, the government will swiftly deliver information to local authorities and broadcasters, Mr Fujimura said.
"We would like people to carry on as normal because the missile won't fall towards Japan if all goes as expected," he said.
Japan was still hoping that North Korea would abandon its plan.
"North Korea's rocket launch clearly violates UN security council resolutions, and also contradicts the UNSC presidential statement issued after the launch in April," Mr Fujimura said.
"If the launch is forced through, Japan will regard it as extremely deplorable."
Meanwhile two US guided missile destroyers have been sent to the area ahead of the launch, an official told AFP.
The two ships were moving in to "monitor any potential missile launch by North Korea and to reassure regional allies should a launch occur," said the official, who spoke on condition of anonymity.
Admiral Samuel Locklear said naval ships had been sent to the region "so we understand if they do violate the UN Security Council [resolution] and launch a missile, what kind is it? What is it about? Where does it go? Who's threatened?"
UN diplomats inside and outside the security council have started consultations behind the scenes on what action to take if Pyongyang goes ahead with the launch, Kyodo News reported.