“The two leaders basically discussed the fact that the United States and China have differences when it comes to Taiwan, but that they have managed those for over 40 years, and that keeping an open line of communication on this issue is essential to continuing to do so,” she said.

As has been the case since reports began circulating about Pelosi’s plans, the White House official would not comment on the House speaker’s trip, saying only that “no trip has been announced and as we said previously, it’s her decision”.

Despite the stern rhetoric, each leader viewed the conversation as “candid, in-depth and constructive”, the embassy said, adding that both sides had instructed their teams to maintain “communication and cooperation”.

The White House official called the talks “substantive”, “in-depth” and “candid”, adding that the two leaders “discussed the value of meeting face-to-face and agreed to have their teams follow up to find a mutually agreeable time to do so”.

Taiwan ‘will have to bear wrath of Beijing’ if Pelosi visit goes ahead

The fifth call between the two presidents since Biden took office last year was intended to manage the rivalry between the two powers. But that aim risked being upended amid reports of Pelosi planning a trip to Taiwan next month. She would be the first US House Speaker to visit the island since Newt Gingrich in 1997.

Beijing said a trip by Pelosi would be more of a violation of its sovereignty over Taiwan than previous visits to the island by US officials and politicians because she is second in the US presidential line of succession.

Chinese Foreign Ministry spokesman Zhao Lijian reiterated the warning ahead of the call on Thursday.

China, US both build up military strength around Taiwan Strait as tensions rise

“China has repeatedly stated to the US its solemn position that it firmly opposes House Speaker Pelosi’s visit to Taiwan,” Zhao told a daily press conference.

“If the US insists on going its own way, the Chinese military will never sit idly by, and will take strong measures to thwart any attempt by external forces to interfere and support Taiwan independence”.

“These calls, while I think constructive and we should be glad that they’re meeting, are not driving events,” said Robert Daly, director of the Wilson Centre’s Kissinger Institute on China and the United States. “The events are unfolding, but the relationship keeps deteriorating quite regardless of these discussions.”

Call between Xi and Biden won’t break China-US deadlock, observers say

The leaders’ call follows a number of incidents in the South China Sea that US officials regard as evidence of Beijing’s increasingly aggressive stance.

However, Xi and Biden “did not have an opportunity to talk in depth about the South China Sea”, the White House official said, even though White House National Security Council spokesman John Kirby said on Wednesday that “tensions in the South China Sea” would be a topic of conversation.

Instead, the leaders did discuss “broadly speaking … concerns about ways in which the Chinese activities are at odds with the international rules-based order, issues surrounding the maritime region”, the White House official said in Thursday’s briefing.

Earlier Kirby described the bilateral relationship as “one of the most consequential” in the world, bearing ramifications “well beyond both individual countries”.

Economy over tariffs: US, China told to be ‘responsible’ global leaders

Xi had “reiterated China’s principled position” on the subject, according to the embassy.

Chinese defence ministry spokesman Wu Qian hit back at US criticisms of Chinese military deployments in the South China Sea.

Wu told a press conference on Thursday that security concerns in the disputed waters had been triggered by “US provocations such as long-term, large-scale and high-intensity reconnaissance and military exercises”.

“China firmly opposes this, and takes reasonable, powerful, safe and professional measures to resolutely respond,” he added. “We urge the US to stop infringements and provocations.”

Wu also criticised US plans to deploy intermediate range missiles in Japan, saying: “This will seriously threaten the security of countries in the region and seriously undermine regional peace and stability. If it is put into practice, China will take firm countermeasures.”

Risk of US-China conflict over Taiwan could leave Japan badly exposed

The foreign minister also warned the US not to make “subversive mistakes that ruin peace across the Taiwan Strait”.

‘Ineffective’ tariffs on Chinese tech imports cost US firms US$32 billion

“So we thought that the previous administration’s approach to tariffs was a shoddy deal,” Kirby added.

However, the White House official briefing reporters after the call said Biden did not end up discussing his plans for the tariffs. The US president instead brought up his “core concerns with China’s unfair economic practices, which harm American workers and harm American families”.

Competing interests tug at Biden as he mulls cutting tariffs on Chinese goods

Whether these tensions could be alleviated by a face-to-face meeting depends on whether the two leaders are able to bring accommodation, however minimal, to the proposed summit, said the Wilson Centre’s Daly.

“The challenge for the United States is to describe some version of a one-China policy that is convincing to China and that we can actually live by and abide by,” Daly said.

On the other hand, Beijing “is not going to give up its claims to Taiwan, but the notion that all of [the Chinese government’s] sensitivities should be honoured at all times by the United States and other countries is clearly not going to wash”, he added.