Donald Trump lands in China on Wednesday for a summit with Xi Jinping that analysts are calling one of the defining diplomatic encounters of his presidency.

Washington’s attention has been elsewhere for much of the past year – consumed by the Iran conflict, operations in the Western Hemisphere and domestic political battles – but Beijing moves to centre stage this week. Global trade, the Taiwan question and the race for technological supremacy are all on the table.

Before leaving Washington on Tuesday, Trump told reporters Iran would be high on the agenda as he promised a “long talk” with Xi on the subject.

China has been working alongside Pakistan to broker a settlement, with the two countries putting forward a five-point peace framework in March that includes provisions for reopening the Strait of Hormuz. Behind the scenes, Chinese officials have been gently nudging their Iranian counterparts towards the negotiating table.

Why does China want an end to the Iran conflict?

Despite its public show of strength, China is eager for the war to end. Slower growth and rising unemployment are already squeezing the Chinese economy, and surging oil prices have added to the pressure – pushing production costs up by 20 per cent for some manufacturers reliant on petrochemicals.

Strategic fuel reserves and China’s dominance in clean energy have cushioned some of the blow, but an economy built on exports cannot escape the war’s consequences indefinitely. If China is to help broker peace, however, it will expect something in return.

Tehran’s decision to send Foreign Minister Abbas Araghchi to Beijing last week was read in Washington as a deliberate display of China’s reach and leverage across the Middle East. “I hope the Chinese tell him what he needs to be told,” said Secretary of State Marco Rubio.

“And that is that what you are doing in the Strait is causing you to be globally isolated. You’re the bad guy in this.”

The US has also been pressing China not to block a new UN Security Council resolution condemning Iran’s attacks on shipping in the Strait of Hormuz, after China and Russia vetoed an earlier proposal.

Ali Wyne, Senior Research and Advocacy Adviser for US-China relations at the International Crisis Group told the BBC: “I think if we’re going to bring Iran back to the negotiating table in an enduring way, I think that the United States recognises that China is going to play some role.”

Despite sanctioning a Chinese refinery over Iranian oil shipments, Trump himself has been notably reluctant to criticise Beijing’s relationship with Tehran. “It is what it is, right?” he told a journalist. “We do things, too, against them.”

What will Trump and Xi discuss about Taiwan?

A £8 billion arms package approved for Taiwan in December infuriated Beijing, yet Trump has simultaneously questioned how far the US would go to defend the island, which China regards as sovereign territory.

“He considers it to be a part of China,” Trump said of Xi, “and that’s up to him, what he’s going to be doing.”

Trump has also questioned whether Taiwan adequately compensates the US for its security guarantees, saying it “doesn’t give us anything,” and imposed a 15 per cent tariff on the island last year, accusing it of taking semiconductor manufacturing from America.

Rubio said Taiwan would feature in this week’s talks, with the aim of ensuring it does not become a new flashpoint between the superpowers.

“We don’t need any destabilising events to occur with regards to Taiwan or anywhere in the Indo-Pacific,” he said. “And I think that’s to the mutual benefit of both the United States and the Chinese.”

China’s Foreign Minister Wang Yi last week urged the US to make the “right choices” on Taiwan during a call with Rubio.

What is at stake on trade between the US and China?

Trade relations spent much of last year on a knife edge, with tariffs on Chinese goods swinging wildly. At one point tariffs breached 100 per cent as the two sides traded economic blows.

Beijing fired back by throttling rare earth exports and pulling back from American farm produce, a move which was interpreted as a deliberate strike at Trump’s rural voter base.

The October face-to-face in South Korea brought the temperature down, and a Supreme Court ruling in February restricting Trump’s ability to impose tariffs unilaterally provided further stability.

On trade, Trump will push for greater Chinese purchases of American farm goods, while Beijing is expected to demand the withdrawal of a US probe into unfair commercial practices — an investigation that could hand Trump the legal basis to restore punishing tariffs.