The Japanese army has set up missile interceptors in Tokyo to protect the capital, amid ongoing speculation that next-door North Korea may conduct a long-range missile launch. The ground-based Patriot Advanced Capability-3 (PAC-3) units have been placed in several parts of Japan besides being stationed in Tokyo.

The Japanese defence ministry has ordered shooting down of any missile cruising in the region. As part of the ramped up security efforts, the Japanese navy has also dispatched an Aegis destroyer, equipped with sophisticated radar and interceptors, to the Sea of Japan. Two of the missile batteries were stationed at the defence headquarters in Tokyo pointed at the sky towards the northwest.

"We cannot rule out the possibility [North Korea] will do something provocative without prior warning, such as launching a ballistic missile. The government's readiness will be rock-solid to protect the people's lives," Chief Secretary Yoshihide Suga told reporters. Governors and other local leaders of prefectures have also been notified over the deployment and the alert.

Earlier, a Japanese official had hinted the defiant North may be preparing for a missile launch at the start of February. The official, quoted by Kyodo news agency, had cited satellite images of the North's Tongchang-ri missile site to back his assertions.

Though South Korea neither confirmed nor denied the alleged preparations, it was quickly followed up by the US, which suspects Pyongyang could be in the early stages of a missile launch. "Our concern though is... it's the same technology to develop ICBMs [inter-continental ballistic missiles]," an unnamed American official told Reuters.