Japan missile
Japan's Defence Minister Itsunori Onodera attends a news conference at Defence Ministry in Tokyo, Japan August 8, 2017. Reuters

Japan deployed its Patriot missile defence system on Saturday after North Korea threatened to fire ballistic missiles over the country towards the US Pacific territory of Guam, reports said.

NHK, the public broadcaster said that the defence ministry started deploying the Patriot Advanced Capability-3 (PAC-3) system in Shimane, Hiroshima and Kochi in western Japan, which Pyongyang warned could be along its missiles' flight path. It also added that Japan was also to deploy the anti-missile system in neighbouring Ehime.

Meanwhile, the regional tensions are mounting as Washington and Pyongyang ratchet up their war of words, with President Donald Trump warning Pyongyang would "truly regret" any hostile action against the US.

Several television footage showed military vehicles carrying launchers and other equipment for the surface-to-air system entering a Japanese base in Kochi before dawn.

In the past, Japan has vowed to shoot down North Korean missiles or rockets that threaten to hit its territory. However, there was no immediate confirmation of the latest reports of deployment.

Kyodo News quoted defence ministry officials as saying that the government hopes to complete deployment of the system in western Japan by Saturday morning.

Eralier this week, Yoshihide Suga, Japan's chief government spokesman, told AFP that Tokyo "can never tolerate" provocations from North Korea and the country's military, will "take necessary measures."

In 2009, a North Korean rocket passed over Japanese territory without incident or any attempt to shoot it down. Although, North Korea claimed that it was launching a telecommunications satellite, but, Washington, Seoul and Tokyo believed Pyongyang was testing an intercontinental ballistic missile.