Chinese leader Xi Jinping has urged Donald Trump to peacefully resolve tensions over North Korea's nuclear programme, as the US president touted the power of a naval "armada" steaming towards the Korean peninsula.Chinese state media said on Wednesday the two leaders had spoken by phone, in an apparent effort to avoid further escalation after Trump deployed the aircraft carrier-led strike group in a show of force.
It headed for the region with a renewed warning that Washington was ready to take on North Korea alone if Beijing declined to help rein in its maverick neighbour's nuclear ambitions.
Pyongyang has so far responded in typically defiant fashion, saying it was ready to fight "any mode of war" chosen by the United States and even threatening a nuclear strike against US targets.
The sabre-rattling has unnerved China, which has made clear its frustration with Pyongyang's stubbornness but whose priority remains preventing any military flare-up that could bring chaos and instability to its doorstep.
In his phone call with Trump, Xi stressed that China "advocates resolving the issue through peaceful means," the foreign ministry said.
On Tuesday, the US president tweeted that "North Korea is looking for trouble. If China decides to help, that would be great. If not, we will solve the problem without them! U.S.A."
A barrage of recent North Korean missile tests has stoked US fears that Pyongyang may soon develop an intercontinental ballistic missile capable of delivering a nuclear warhead to the US mainland.
There is speculation that Pyongyang could be preparing a missile launch, or even another nuclear test, to mark the 105th birthday anniversary of its founder Kim Il-Sung on Saturday.
In an interview with Fox Business Network, Trump warned: "We are sending an armada. Very powerful."
"We have submarines. Very powerful. Far more powerful than the aircraft carrier."
The flotilla includes the Nimitz-class aircraft supercarrier USS Carl Vinson, a carrier air wing, two guided-missile destroyers and a guided-missile cruiser.
"This goes to prove that the US reckless moves for invading the DPRK have reached a serious phase," a spokesman for the North's foreign ministry said in response.
China's Global Times newspaper, which is often nationalistic in tone, said a new nuclear test would be a "slap in the face of the US government" and that Beijing would not "remain indifferent" to further provocations.
Pyongyang has so far staged five nuclear tests, two of them last year, and analysis of satellite imagery suggests it could be preparing for a sixth.
"Presumably Beijing will react strongly to Pyongyang's new nuclear actions," the newspaper said, adding there was increasing popular support for "severe restrictive measures that have never been seen before".
The language suggested China -- the North's sole major ally and economic lifeline -- could restrict oil imports to the North, after already announcing a suspension of all coal imports until the end of the year.
The phone call between the leaders of the world's largest economies followed their first face-to-face meeting late last week.
During their call, Xi told Trump that China remains "willing to maintain communication and coordination with the American side on the issue of the peninsula," according to the foreign ministry.
Trump, it added, said it was vital for the two heads of state to maintain close ties, and that he agreed the US and China should work together to "expand pragmatic cooperation in a wide range of areas".
The high-profile summit was overshadowed by a missile strike on Syria that Trump launched as he hosted Xi.
The move, which came in retaliation for the Damascus regime's suspected sarin attack against civilians in a rebel-held town in Syria, was widely also interpreted as a warning to North Korea.
Xi told Trump on the call that the Syria issue "must continue to move towards a political solution", and that "any use of chemical weapons is unacceptable".
He said their summit produced "significant results", and that both sides would work together to ensure Trump visited China later this year.
Trump's election campaign was marked with acerbic denouncements of the Asian giant's "rape" of the US economy and his vow to punish Beijing with punitive tariffs.
But he dropped his anti-China bombast in Florida, afterwards hailing an "outstanding" relationship with his Chinese counterpart.