WASHINGTON • The Pentagon has endorsed a plan to invest nearly US$8 billion (S$11.2 billion) to bulk up the United States' presence in the Asia-Pacific region over the next five years by upgrading military infrastructure, conducting additional exercises and deploying more forces and ships, according to The Wall Street Journal.

The effort is seen by backers as one way to signal more strongly the US commitment to the region as Washington confronts an increasingly tenuous situation on the Korean peninsula, its chief security concern in the area.

The Trump administration is still formulating its larger policy for Asia after essentially discarding former president Barack Obama's so-called Asia pivot, which was disparaged by critics as thin on resources and military muscle, and dropping US support for the Trans-Pacific Partnership, a 12-nation trade deal.

Given President Donald Trump's recent overtures to Chinese President Xi Jinping, any plan to expand the US military presence in Asia eventually may require steps to reassure Beijing that new military measures aren't directed at the Chinese. A spokesman for China's embassy in the US didn't immediately respond to a request for comment.

The proposal, dubbed the Asia-Pacific Stability Initiative, was first floated by Senator John McCain and has been embraced by other lawmakers and, in principle, by Defence Secretary Jim Mattis and the head of US Pacific Command, Admiral Harry Harris. Proponents, however, have not developed details of the US$7.5 billion plan.

"This initiative could enhance US military power through targeted funding to realign our force posture in the region, improve operationally relevant infrastructure, fund additional exercises, pre-position equipment and build capacity with our allies and partners," Mr McCain told Adm Harris in an April hearing, the Journal reported.

Meanwhile, US Pacific Fleet Commander Scott Swift was reported by news agency Bloomberg as saying that a hiatus in "freedom of navigation" operations in the South China Sea under Mr Trump's presidency does not mean the disputed waterway is becoming a diminished priority for the US.

"We just went through a change in administration," Adm Swift said yesterday in a briefing in Singapore. "I am not surprised that process has continued in a dialogue as the new administration gets its feet on the ground and determines where would be appropriate to take advantage of these opportunities and where we may want to wait."