U.S. Secretary of Defense Chuck Hagel will focus on the North Korea issue when he holds trilateral talks with his South Korean and Japanese counterparts in Singapore later this week, officials said Tuesday.

Hagel is scheduled to fly to Singapore on Friday to attend the Shangri-La Dialogue, an annual gathering of top defense officials mainly from the U.S. and Asian nations.

It would be his first trip to Asia since taking office in February.

"We always talk about the regional security situation and obviously North Korea is always a centerpiece of that with those two allies," a senior Pentagon official told reporters on the customary condition of anonymity.

Tensions and uncertainly on the peninsula, caused by North Korea's recent provocations and threats, will be by far the dominant agenda item, added the official.

Also to be discussed in Hagel's meeting with Kim Kwan-jin of South Korea and Itsunori Onodera of Japan, slated for Saturday, are trilateral exercises, disaster relief, counter-proliferation and counter-piracy, according to the official.

Hagel also plans to have a tripartite meeting with his Australian and Japanese counterparts and several bilateral talks on the sidelines of the security forum.

The issue of beefing up regional missile defense to counter North Korea's threats is expected to be raised in those discussions, the official said.

But the U.S. has no plans for formal bilateral talks with China in Singapore, as Beijing is sending a delegation headed by a top military official, not its defense minister.

Japan also sought to hold a bilateral ministerial meeting with South Korea on the margins of the Singapore forum, but South Korea rejected the offer, an informed source said. Political ties between Seoul and Tokyo show no signs of improving amid a public furor in South Korea over the historical views of the conservative Shinzo Abe administration and other leading politicians in Japan.

Asked if Hagel has a plan to deliver a message to South Korea and Japan on their soured relationship, the official avoided a direct answer, only saying the U.S. alliances with the two Asian nations are cornerstones of its regional security strategy.

Meanwhile, Hagel's aides stressed that the secretary has personal ties with Asia, having taken part in the Vietnam War. As a senator, he also helped found the Shangri-La Dialogue a decade ago.

"For all those reasons, he is personally committed to the security of the region," another Pentagon official said on background.

Hagel will visit Hawaii, home of the Pacific Command, on his way to Singapore. After a four-day stay in Singapore, he will head to Brussels for the NATO defense ministers' meeting. (Yonhap News)