The US Secretary of State said decades of US alliances and investment had helped Asia walk from poverty to prosperity, as he aired the Trump administration's "Indo-Pacific" strategy in Bangkok.

From supporting state-led enterprises to disputes over contested territories, Pompeo took aim at China's actions and motivations in Southeast Asia, rowing back on comments on Thursday in which he told regional diplomats they were not expected to "choose" sides between the superpowers.

"Our investments don't serve a government.... (they) don't serve a political party," he said of the Chinese Communist Party.

Beijing considers Southeast Asia as its "neighbourhood" where its economic, political and military might has given it primacy, with massive infrastructure and investment schemes striating the region.

But smaller powers also accuse China of loading on debt as well as aggression in the disputed South China Sea where a military build-up threatens the claims of several nations to strategically crucial waters.

The US wants the South China Sea, one of the world's most important shipping lanes, to remain open.

Serving up a sharp rebuke on China's drive into Southeast Asia, Pompeo said: "We're not building roads to pave over your national sovereignty... We don't fund bridges to close gaps of loyalty."

His speech came hours after President Donald Trump promised to slap 10 percent of new tariffs on $300 billion of Chinese goods in a sharp escalation of the trade war between the two superpowers.

In short panel comments after his speech, Pompeo accused China of "protectionism" and "predatory tactics" to give its companies an advantage in global markets.

"China has taken advantage of trade... It's time for that to stop," he said.

"I think that's what you saw this morning," he added, referencing Trump's latest barrage of tariffs on Chinese goods.

He also stuck to Washington's position of non-interference on the massive anti-government protests engulfing Hong Kong, a Chinese territory.

"I hope that the way things will proceed in Hong Kong... will be non violent."

Asked what the US response would be in the event of a Chinese military intervention in the financial hub, he said: "One thing this administration has been really good about is not tipping our hand to what we will or won't do. And I'm going to do that here this morning."

Pompeo is in Bangkok to attend the Association of Southeast Asian nations (ASEAN) foreign ministers meeting.