Pentagon chief Chuck Hagel will reassure allies in a trip to Asia this week that the United States intends to '"follow through" on its promised strategic shift to the Pacific region, officials said Tuesday.

In his first trip to the area since he took over as defense secretary in February, Hagel was expected to discuss Washington's "rebalance" towards Asia and recent tensions with North Korea in meetings with his counterparts at a Singapore conference.

"The focus is really follow through this year," said a senior defense official, who spoke on condition of anonymity.

"Last year, we were sharing with the region the new strategic guidance. This year is really about showing that that strategic guidance, the rebalance, is under way," the official told reporters.

President Barack Obama last year unveiled a new security strategy that emphasized a shift towards the Asia region, reflecting worries over China's growing military power.

But a budget impasse in Washington has triggered automatic cuts to US military spending, raising concerns in Asia that America's promised rebalance could be derailed.

At the Shangri-La Dialogue in Singapore, an annual summit organised by the London-based International Institute for Strategic Studies, Hagel was due to meet numerous defense ministers from the region and deliver a policy speech on Saturday.

At last year's Singapore summit, former defense secretary Leon Panetta announced that the majority of the US naval fleet would be gradually shifted to the Pacific region as part of the pivot to Asia.

Hagel was scheduled to hold bilateral talks with counterparts from the Phillipines, South Korea, New Zealand, Singapore, Indonesia, Malaysia as well as Vietnamese Prime Minister Nguyen Tan Dung.

He also will hold a trilateral meeting with ministers from Japan and South Korea.

"We have a lot to talk about in terms of shared security interests, especially given some recent provocations and provocative rhetorick from North Korea," the US official said.

North Korea reacted to joint US exercises with South Korea in March and April with a new round of bellicose rhetoric, including dire threats of nuclear war from Pyongyang.

The North has since toned down its language in recent weeks and US officials say medium-range missiles were no longer poised for launch.

With Western governments debating a possible intervention in Syria's civil war, Hagel also will meet several European counterparts in Singapore, including defense ministers from Britain, France and Germany.

In Singapore, the Pentagon chief is due to pay a visit to the USS Freedom, the first of the new Littoral Combat Ships that will be based out of the port. The ship deployments are touted as part of the US strategic focus on Asia.

Hagel departs Wednesday from Washington and will stop in Hawaii to visit troops and meet the head of US Pacific Command before heading to Singapore. After the security summit, the former senator travels to Brussels for a meeting of alliance defense ministers on June 4-5.