Japan threat against North Korea
Units of Patriot Advanced Capability-3 (PAC-3) missiles stand at the Defence Ministry in Tokyo, JapanKyodo via Reuters

The Japanese military is on high alert and has been ordered to shoot down any object violating its territory. Tokyo's warning comes as North Korea is believed to be gearing up for a long-range rocket launch.

Japan's Defence Minister Gen Nakatani exhorted missile interceptor units and the Aegis destroyer in the Sea of Japan (East Sea) – which were recently mobilised to confront Pyongyang – to be on alert for any flying objects. A statement from the ministry said Gen had ordered destruction of the rocket if it "is confirmed that it will fall on Japanese territory".

The rocket is likely to pass over Sakishima Islands in Japan's southern prefecture of Okinawa if it follows the planned path. The first stage will fall into the waters off the west coast of South Korea while the second stage will find the waters near the Philippines if the rocket is successfully launched by the North as planned.

Tokyo has already deployed Patriot Advanced Capability-3 (PAC-3) missile launchers in Okinawa. Two of the missile batteries were placed in the defence ministry headquarters in Tokyo. Tensions in the region escalated after North Korea notified UN agencies that it is planning to launch an Earth observation satellite anytime between 8 and 25 February.

One of the possible dates on which Pyongyang would fire its rocket is speculated to be 16 February, the birthday of former leader Kim Jong-il. The launch is widely considered a clandestine mission for testing its ballistic missile programme.

Japan's Prime Minister Shinzo Abe earlier condemned the North's plans. He told parliament: "If North Korea goes ahead and launches the rocket, it would clearly violate UN Security Council resolutions and pose a serious provocation. The reality is that it is a launch of a ballistic missile."