But this visit also comes as many countries around the world fear the imposition of punitive tariffs. Sweeping levies Trump announced in April were mostly suspended, as Washington engages in negotiations with friends and foes alike.

On Monday, Trump said he would impose 25 per cent tariffs on key US allies Japan and South Korea and a handful of others, including Southeast Asian nations Malaysia (25 per cent) and Laos (40 per cent), as of August 1.

Export-dependent Vietnam, which like Malaysia and Laos is a member of the Association of Southeast Asian Nations (Asean), is one of the few countries to already reach a tentative agreement with Washington that spares it the high level of levies that Trump had threatened.

At a summit in late May, Southeast Asian leaders expressed their deep concern at Trump's protectionist offensive.

The senior US official said the issue was expected to be raised, and that Rubio would likely tell Asean that the United States wants to "rebalance" its trade relationships.

Rubio's visit to Kuala Lumpur Thursday and Friday coincides with that of his Russian and Chinese counterparts, Sergei Lavrov and Wang Yi.

While there, Rubio is scheduled to attend a meeting with his counterparts from Asean and with a gathering of both Asean and East Asian foreign ministers.

Last week, Rubio welcomed foreign ministers from Australia, India and Japan to Washington, where they pledged to work together to ensure a stable supply of critical minerals.

China's domination of such resources – essential to new technologies – is causing increasing concern in western Europe and the United States.