PALM BEACH, United States — US President Donald Trump ditched his trademark anti-China bombast, hailing an "outstanding" relationship with counterpart Xi Jinping at the end of a superpower summit Friday overshadowed by events in Syria.

"We have made tremendous progress in our relationship with China," Trump said effusively at the close of a high-stakes but studiously familiar first meeting between the pair at his Mar-a-Lago resort in Florida.

"I think truly progress has been made," Trump said, declaring his relationship with Xi as "outstanding".

The friendly tone was a far cry from Trump’s acerbic campaign denouncements about China’s "rape" of the US economy and his vow to punish Beijing with punitive tariffs.

Xi reciprocated Trump’s warm words, saying the summit had "uniquely important significance" and thanking Trump for a warm reception.

Xi also invited the US president on a coveted state visit to China later in the year. Trump accepted, with a date yet to be determined.

We "arrived at many common understandings," Xi added, "the most important being deepening our friendship and building a kind of trust".

The bonhomie extended behind closed doors, where the US president’s grandson and granddaughter sang a traditional Chinese ballad -- "Jasmine Flower" -- and recited poetry for their honoured guests, earning praise from their "very proud" mother Ivanka in a tweet.

"Both the atmosphere and the chemistry between the two leaders was positive, the posture between the two really set the tone," said Secretary of State Rex Tillerson.

"All of us are feeling very good about the results of this summit."

Winter White House

The start of the meeting came on a night of high drama as Trump not only met his nearest peer in economic world power for the first time but also launched his first military strike on a state target.

Trump informed the Chinese leader personally of the strike as the 59 Tomahawk missiles were winding their way to the Shayrat airbase.

Although China is not implicated in the Syrian war, Trump’s actions resonate widely, not least in the debate over how to tackle North Korea’s nuclear and ballistic missile programmes.

China and the United States agree Pyongyang’s programmes are a serious problem, but have not seen eye-to-eye on how to respond.

"There is a real commitment to work together to see if this cannot be resolved in a peaceful way," said Tillerson.

Trump asked Xi for ideas on how to proceed, but held out the possibility of unilateral action.

"(We) are prepared to chart our own course if this is something China is just unable to coordinate with us," said Tillerson.

Iran’s President Hassan Rouhani meanwhile said that "terrorists" were applauding Trump for launching a missile strike on an airbase of his Syrian government ally.

But he backed calls for an independent inquiry into a suspected chemical weapons attack on a rebel-held town in northwestern Syria on Tuesday that Trump blamed on the Damascus regime.

"This man who is now in office in America claimed that he wanted to fight terrorism but today all terrorists in Syria are celebrating the US attack," Rouhani said in a speech aired by state television.

"Why have you attacked the Syrian army which is at war with terrorists? Under what law or authority did you launch your missiles at this independent country?" — AFP