TOKYO - New guidelines governing the Japan-US defence alliance should allow the two militaries to "seamlessly co-operate", American Defence Secretary Ashton Carter told a newspaper ahead of a meeting Wednesday with his Japanese counterpart in Tokyo.
On the second day of a three-day visit to Japan, Carter was meeting with Defence Minister Gen Nakatani to thrash out new guidelines governing the way their countries' militaries work together.
The move comes as Japanese Prime Minister Shinzo Abe is pushing for a higher profile regional role for Japan at a time of growing disquiet in Asia over the rise of a newly-assertive China.
The guideline revisions the two men were discussing Wednesday will be officially completed in Washington at the end of April, when Abe visits the US, along with Nakatani and Foreign Minister Fumio Kishida.
The revisions will expand opportunities for the United States' military to "seamlessly co-operate" with Japan's Self Defence Forces, Carter said in a written interview with the mass-selling Yomiuri Shimbun.
The rules, which were last revised in 1997, will take into account a constitutional re-interpretation by the Abe government last year, which allows for so-called "collective defence".
This change "has informed" the new framework, a senior US official travelling with Carter said.
Under the new constitutional interpretation, Japan's military will be permitted, in certain circumstances, to come to the aid of an ally under attack.
Previously, governments have held that they can only fight back if directly attacked, or in defence of Japanese nationals or property.
The new guidelines will improve "the Japanese ability to defend US forces under certain circumstances", if they come under military attack, the official said.
Also co-operation will be enhanced in "information sharing, ISR (intelligence, surveillance and reconnaissance), training," he added.
Abe has faced considerable domestic opposition to his bid to weaken the Japanese constitutional commitment to pacifism.
He gave up an original plan to amend articles restricting the country's well-armed and well-trained military to a narrowly-defined defensive role, and settled for reinterpreting the rules instead.
The United States has around 47,000 service personnel stationed in Japan, a legacy of the US occupation of its former adversary at the end of World War II.