The report on the defence planning states that: "The committee recognises the strategic importance of providing ballistic missile defence for Guam and the current US asset based there.

"The committee further recognises that as part of bilateral negotiations with the government of Japan, the US military presence on the island and the need to protect it from missile threat are projected to increase."

Thaad systems and Patriot interceptor missiles have been stationed on Guam in the past, supplementing warships, but the report cites the "immediate threat of missiles launches from the Democratic People's Republic of Korea toward US military assets on Guam" as reason for the move.

Politicians on Guam also requested that it have permanent missile systems as defence against North Korean missiles.

However, Go Ito, a professor of international relations at Tokyo's Meiji University said: "My feeling is that while they may be naming North Korea, this is more aimed at China.

"North Korea has missile technology and there are concerns about political stability in Pyongyang at the moment, but China has developed its own missile capabilities, so that is the bigger concern for the US.

"These missiles are targeted at any prospective threats that China might pose in the future," he said. "And putting them on Guam does away with the possibility of causing new political problems in Okinawa."

Siting missiles in Guam was the latest move in the military game of chess that was being played out in the region, he added.

"But I'm actually quite optimistic about how things will play out," he said. "Both China and Japan know that a military confrontation will only have negative consequences.

"That is, admittedly, based on a rational calculation and such rational calculations are not always equal on both sides, but I believe China understands that it benefits from foreign direct investment into its economy and that its development is still quite fragile."