SINGAPORE — Many countries, especially those in Southeast Asia, want to maintain “strong links” with the U.S. — and Washington shouldn’t force them to choose sides in its rivalry with Beijing, a prominent former Singapore diplomat said on Monday.

“Trump’s erratic policies towards China, especially putting countries in a difficult position having to choose between China and the U.S., made everybody very, very uncomfortable,” Kishore Mahbubani, now a distinguished fellow at the National University of Singapore’s Asia Research Institute, told CNBC’s “Squawk Box Asia.”

U.S.-China relations worsened significantly after President Donald Trump took office in 2017. The U.S. has in some instances sought to bring countries to its side against China.

One example is Washington’s call to countries to ban Chinese tech firm Huawei from their 5G networks, citing threats to national security.

In the lead up to last week’s election, Secretary of State Mike Pompeo — who was visiting several Asian countries — gave a series of speeches that attempted to bolster U.S. allies against China.

In Southeast Asia, several surveys conducted before the coronavirus pandemic showed China’s economic and political influence in the region surpassing that of the U.S. That gap could grow even wider in the coming years.

But the U.S. has invested heavily in the region, and Southeast Asian countries would continue to welcome Washington, said Mahbubani, who spent 33 years as a Singapore diplomat before joining academia in 2004. Among the appointments that he held were Singapore’s ambassador to the United Nations and president of the UN Security Council.

“So, this place, there’s lots of reservoir of goodwill towards the United States … which the United States can actually tap on,” he said.

But the U.S. must “play the long game” and not force countries to choose sides, he added. He explained that the U.S. can be better off working with partners, such as Southeast Asian countries, to set the global rules that everyone — including China — must conform to.

Southeast Asia is home to more than 650 million people and some of the world’s fastest-growing economies. Its proximity to the South China Sea — a vital commercial shipping route where trillions of dollars of the world’s trade passes through — adds to the region’s strategic importance.     

The U.S. has for many years been an important presence in the region through both security and economic engagements. But since Trump took office, the U.S. withdrew from the Trans-Pacific Partnership or TPP — a mega trade pact that included several Southeast Asian countries.

In another sign that the U.S. commitment to the region may be waning, top American government officials have been notably absent at a few important regional summits.

Mahbubani said involvement in the TPP would have allowed the U.S. to entrench its position in East Asia for the long haul. But it’ll be “very difficult” for President-elect Joe Biden to return the U.S. into the mega trade deal, he added.

“I think if Biden could make the decision privately and independently, he would love to go back and join the TPP. But he’ll be massacred domestically because, as you know in the United States, the political environment against free trade agreements has become very, very toxic,” he said.