This week, the United States and Japan will discuss ways to deal with a broad range of regional security threats, including territorial tensions with China and the North Korea issue, as the allies study how to revise bilateral defense cooperation guidelines, officials said Monday.

The two sides opened an inaugural working group meeting in Hawaii to follow up on a landmark deal between their foreign affairs and defense chiefs in October. In the so-called two-plus-two session, Washington and Tokyo agreed to revise the guidelines, last updated in 1997, by the end of this year.

In a joint statement issued after the 2013 meeting, Japan said it was re-examining the legal basis for exercising its right of collective self-defense, which would enable Japan's Self-Defense Forces to engage in offensive military operations abroad with the U.S. or other partner nations.

While the U.S. formally welcomed the move, it has triggered a wave of concern, especially in South Korea and China amid the Shinzo Abe administration's campaign to expand the role of Japan's military.

"The collective self-defense issue will be discussed in the defense guidelines revision meeting in Hawaii to last through Thursday," a Pentagon official told Yonhap News Agency, requesting anonymity.

Particularly high on agenda is to characterize "gray zone" incidents, which refer to cases happening neither at war nor in peace time.

Japanese officials apparently use the term mainly to describe potential conflicts with China over a chain of islands in the East China Sea, called the Senkaku by Tokyo and the Diaoyu by Beijing.

But U.S. military officials have broader issues, including North Korea's provocations, in mind.

"Since this week's meeting is an inaugural session, we don't expect any specific deal," the official said. "The two sides will continue related consultations."

In the next sessions, the issue of a much-needed military intelligence sharing agreement between South Korea and Japan will likely be raised, added the official.

The Pentagon withheld the list of participants in the Hawaii meeting. A source said the delegations of the U.S. and Japan are led by director general-level officials. (Yonhap)