President Donald Trump reaffirmed Washington's 'One China' policy in his first conversation with Xi Jinping, an apparent effort to ease tensions after angering Beijing by questioning a major plank of Sino-US relations.

During a phone call with China's leader, the US president agreed to "honor" a position that effectively acknowledges Taiwan is not separate from China.

"President Trump agreed, at the request of President Xi, to honor our 'One China' policy," the White House said in a statement, adding that the two leaders had "extended invitations to meet in their respective countries."

The White House called the phone discussion -- which came on the eve of Trump's slated meeting with Japanese Prime Minister Shinzo Abe -- "extremely cordial," saying the leaders "look forward to further talks with very successful outcomes."

Xi, a nationalist who took the helm of the Communist Party-ruled country in 2012, welcomed Trump's gesture.

"Xi Jinping appreciates Trump’s emphasis on the American government’s commitment to the One China policy and pointed out that the One China principle is the political foundation of US-China relations," according to a Chinese foreign ministry’s statement.

Trump's insurgent campaign for the White House included frequently lashing out at China, which he accused of currency manipulation and stealing American jobs.

He raised eyebrows in the wake of his election victory with a protocol-busting telephone conversation with Taiwan's President Tsai Ing-wen.

He later threw doubt on the "One China" policy, suggesting that it was up for negotiation and could form part of talks on trade, drawing rebukes from official Chinese media.

- 'Backed Down' -

Ashley Townshend, an expert in US-China relations at the University of Sydney said Trump's apparent capitulation was an indication of the moderating influence of Secretary of State Rex Tillerson and Defence Secretary James Mattis.

"Everyone will be surprised at the speed with which Trump has backed down on this issue, everyone is asking why he has moderated his position so dramatically," he said.

The change was unlikely to be conciliatory, he added, but could be read as a sign of pragmatism in the new administration's approach to its powerful adversary.

There was a real risk prior to this clarification that the two sides would be unable to even find a way to speak," he said.

"There are many advisors in Trump’s inner circle and in the administration more generally who are deeply suspicious of China.

"I suspect Trump will continue to be tough on China across many aspects of the bilateral relationship. This removes an obstacle to relations, but it doesn’t advance them in any meaningful way."

Taiwan has been ruled separately since the two sides split in 1949 at the end of a civil war.

Despite having its own government, military and independent foreign policy, Beijing has refused to recognise the island, viewing it as a troublesome province that will one day be reunited with the mainland -- by force, if necessary.

Washington cut formal ties with Taipei in 1979, when it recognized the Communist mainland rulers in Beijing.

However, the US remains Taiwan's most powerful unofficial ally and its main supplier of arms.

Trump's suggestion that he could restore relations with Taipei -- which Beijing views as a non-starter -- had threatened to chill ties with the Asian giant.

- 'Come to his senses' -

Beijing had been prepared to give Trump-the-candidate a pass, said Wu Xinbo, Director of the Center for American Studies at China's Fudan University.

"When Trump tweeted a few things about the "One China" policy previously, it was prior to his inauguration, so we can consider those his personal opinion," said Wu.

"Now that he is in office, he represents the government’s views, and as such, he must emphasize the continuity of policies such as the Taiwan issue and the One China issue."

Xu Guoqi, an expert in Sino-US relations at the University of Hong Kong, said Thursday's call showed the US president had "come to his senses" about a policy that had underpinned ties since Richard Nixon occupied the Oval Office.

"Trump had no idea what he was talking about before. He benefited from his lousy mouth to get elected, but afterwards he kept talking without caring about consequences and about whether what he was saying was correct or not," he said.

"Without honoring the 'One China' policy, the relationship only has one way to go: down to hell. 

"Now with the phone call and promise to honor the One China policy I think now the two sides can assume business as usual. They are back to square one."

Source: AFP