HONOLULU: Japan's defence minister is in Hawaii to meet with senior US military officials for the first time since his country's parliament approved legislation loosening post-World War II constraints on its military.

Defence Minister Gen Nakatani was scheduled to meet with US Pacific Command commander Adm. Harry Harris on Tuesday. The Pacific Command said Nakatani's discussions were expected to cover security in the region, including in the East and South China Seas. Ballistic missile defense was also on the agenda.

Japan's parliament passed legislation in September allowing Tokyo's military to defend its allies even when the country isn't under attack. The law will enable Japan to work more closely with the US and other nations.

Ralph Cossa, president of the Pacific Forum CSIS think tank, said the two allies need to determine how the law will work when it comes to operations. That's likely to be a topic of Nakatani's discussions in Hawaii, he said.

"People are still curious as to what the two are going to be able to do together," Cossa said.

Ballistic missile defence is one area where increased cooperation is expected.

"With the new legislation, presumably now if the North Koreans shoot a missile toward Hawaii, and the Japanese detect it, they can shoot it down. Before they just had to just sort of wave to it as it went by," Cossa said.

Japan has invested heavily in missile defences since North Korea test-fired a ballistic missile over Japan's main island in 1998. Nakatani's schedule in Hawaii included a visit to the Sea-based X-band Radar — which is used to detect ballistic missiles — at Pearl Harbor.

The new law would also allow Japan to help defend a US ship under attack. The US has long been able to help a Japanese ship in the same situation, but Japan's prohibitions against collective self-defence didn't allow the reverse.

The legislation sparked protests and debate in Japan about whether Tokyo should shift away from its pacifist ways to face growing security challenges.

The law's supporters say Japan's neighborhood has become a more dangerous place, citing North Korean missile tests and Chinese challenges to Japanese sovereignty over remote islands.

They say Japan's military needs to be more active to deter China and North Korea and help preserve Japan's peace and prosperity. A major goal of the legislation is to allow the military to work more closely with its main ally, the United States, strengthening their joint capabilities.