"There's a big deal to be done at some point" Bessent said when asked by Bloomberg TV about the possibility that the world's largest economies would decouple.

"There doesn't have to be" decoupling, he said, "but there could be."

Bessent stressed that a deal with China would be more difficult than with other nations because "China is both our biggest economic competitor and our biggest military rival."

The world's two largest economies have been locked in a fast-moving game of brinkmanship since US President Donald Trump launched a global tariff assault that particularly targeted Chinese imports.

Tit-for-tat exchanges have seen US levies imposed on China rise to 145 percent, with Beijing setting a retaliatory 125 percent band on US imports.

The US side has sent mixed messages about what it wants to achieve and whether tariffs that would rock the world economy can be avoided.

The White House had appeared to dial down the pressure recently, listing tariff exemptions for smartphones, laptops, semiconductors and other electronic products for which China is a major source.

But Trump and some of his top aides said Sunday that the exemptions had been misconstrued and would only be temporary as his team pursued fresh tariffs against many items on the list.

"NOBODY is getting 'off the hook'... especially not China which, by far, treats us the worst!" he posted on his Truth Social platform.

Bessent warned that Trump's tariffs were "not a joke."

"These are big numbers. I think no one who thinks they're sustainable wants them to remain here."

China's Xi Jinping on Monday kicked off a Southeast Asia tour with a visit to Vietnam -- where he warned that protectionism "will lead nowhere" and a trade war would "produce no winner."

"We must strengthen strategic resolve, jointly oppose unilateral bullying, and uphold the stability of the global free trade system as well as industrial and supply chains," Xi told Vietnam's top leader, To Lam.

The White House has said Trump remains optimistic about securing a trade deal with China, although administration officials have made it clear they expect Beijing to reach out first.

The trade war is raising fears of an economic downturn as the dollar tumbles and investors dump US government bonds, normally considered a safe haven investment.