WASHINGTON US Secretary of State Antony Blinken and Defense Secretary Lloyd Austin will head to Asia this week to reassure allies and partners of US support, the State Department's top official for East Asia said on Monday, as the November US presidential election casts uncertainty over Washington's foreign policy.

US tensions with China will provide the backdrop to the trip. Blinken is expected to meet his Chinese counterpart Wang Yi on the sidelines of regional meetings in Laos, Assistant Secretary of State Daniel Kritenbrink told reporters.

Blinken and Austin will hold security talks with US allies Japan and the Philippines. Blinken will also visit Singapore and Mongolia, and stop in Vietnam for the funeral of Nguyen Phu Trong, head of the ruling Communist Party, who died last week.

The trip follows a tumultuous month in Washington. US President Joe Biden announced on Sunday that he will not run for re-election, and endorsed his vice president, Kamala Harris, to replace him. The Republican nominee, former president Donald Trump, earlier survived an assassination attempt.

Asked what Blinken will say to allies about Biden's decision to step aside and whether that could bring changes in policy, Kritenbrink said the message would be that America is "all-in on the Indo-Pacific".

"We do try to reassure allies and partners that there are certain fundamentals, I think, about America's engagement that are not going to change, that have been consistent," he said, citing American investments and bipartisan support in Washington for the administration's approach to the region.

Trump, who has been leading in the polls ahead of the Nov 5 election, launched a trade war against China while in the White House, and as a candidate, has suggested he would impose tariffs of 60% or higher on all Chinese goods.

He has also signalled that he would demand Taiwan to boost its defence spending in the face of potential Chinese aggression. Allies of the former president have assured Japan and South Korea that he would continue Biden's engagement with them, aimed at countering China and North Korea.

In Laos, Blinken will attend meetings of the Association of Southeast Asian Nations (Asean) on Friday and Saturday, where China's Wang and Russian Foreign Minister Sergei Lavrov are also expected to attend. A North Korean official would also likely be in attendance, Kritenbrink said.

In Laos, officials are expected to discuss the conflict in Myanmar after the military seized power three years ago. The US expects Myanmar to be represented by a non-political official, as it has been at previous meetings since the coup, Kritenbrink said.

Kritenbrink said Washington welcomed an announcement by Manila on Sunday that it had reached an understanding with China on the resupply of a Filipino naval ship beached on the Second Thomas Shoal.

In Tokyo, Blinken and Austin will meet Japanese counterparts on July 28 and focus on the implementation of agreements reached at an April Washington summit between Biden and Japanese Prime Minister Fumio Kishida.

There, the allies announced plans to upgrade their military alliance, including the US military command in Japan, and more joint development of defence equipment, amid shared concerns about China and Russia.

Tokyo wants a four-star US commander in Japan to match the rank of the head of a new Japanese headquarters that will oversee all of Japan's military operations from 2025. Experts say that could lay the groundwork for a future unified Japanese-US command.

The US has said it would commit to match Japan's planned command upgrade, but experts say there have been questions as to where a four-star US commander for Japan would be based.

Kritenbrink said "command and control" would be discussed, and added: "there'll be discussions about our roles and missions and capabilities; how the alliance is postured to meet those challenges".

"The United States and Japan are going to demonstrate in a responsible way, how we will stand up and ensure not just the defence of Japan, but also our contribution to regional security."

  - Reuters