“The Chinese side has always opposed the use of force in international relations and has advocated the adherence to the Charter of the United Nations, and to resolve problems through political and diplomatic channels,” Chinese Foreign Ministry spokesperson Geng Shuang said.

“The sovereignty, independence, unification and territorial integrity should be respected and protected. We urge Turkey to halt military action and to return to the right track solving the issue with political solutions,” he said.

“The current anti-terrorism situation in Syria is still severe, and related military operation may cause an spillover of terrorists, and cause the comeback of Islamic State who may exploit the situation,” Geng added. “We urge Turkey to take up responsibility, work with the international community in fighting against terrorism.”

Thousands flee, hundreds reported dead in Turkish attack on Syria

Trump said the approximately 1,000 US troops who had been partnering with local Kurdish fighters to battle Isis in northern Syria were leaving the country.

Turkey began attacks in Syria last week against the Syrian Kurdish fighters, whom the Turks view as terrorists. On Monday, Syrian government troops moved north toward the border region, setting up a potential clash with Turkish-led forces.

Trump said Turkey’s invasion is “precipitating a humanitarian crisis and setting conditions for possible war crimes”, a reference to reports of Turkish-backed fighters executing Kurdish fighters on the battlefield.

The Kurdish forces previously allied with the US said they had reached a deal with President Bashar Assad’s government to help them fend off Turkey’s invasion, a move that brings Russian forces deeper into the conflict.

In his sanctions announcement, Trump said he was halting negotiations on a US$100 billion trade deal with Turkey and raising steel tariffs back up to 50 per cent. Trump also imposed sanctions on three senior Turkish officials and Turkey’s defence and energy ministries.

“I am fully prepared to swiftly destroy Turkey’s economy if Turkish leaders continue down this dangerous and destructive path,” Trump said.

Treasury Secretary Steven Mnuchin said the sanctions will hurt an already weak Turkish economy. Pence said the US will continue to ramp up the sanctions “unless Turkey is willing to embrace a cease-fire, come to the negotiating table and end the violence”.

France and Germany halt arms exports to Turkey

US troops consolidated their positions in northern Syria on Monday and prepared to evacuate equipment in advance of a full withdrawal, a US defence official said.

The official, who was not authorised to be quoted by name, said US officials were weighing options for a potential future counter-Isis campaign, including the possibility of waging it with a combination of air power and special operations forces based outside Syria, perhaps in Iraq.

The hurried preparations for a US exit were triggered by Trump’s decision Saturday to expand a limited troop pullout into a complete withdrawal.

Defence Secretary Mark Esper on Monday said he would travel to Nato headquarters in Brussels next week to urge European allies to impose “diplomatic and economic measures” against Turkey – a fellow Nato ally – for what Esper called Ankara’s “egregious” actions.

Esper said Turkey’s incursion had created unacceptable risk to US forces in northern Syria and “we also are at risk of being engulfed in a broader conflict”.

The only exception to the US withdrawal from Syria is a group of perhaps 200 troops who will remain at a base called Tanf in southern Syria near the Jordanian border along the strategically important Baghdad-to-Damascus highway. Those troops work with Syrian opposition forces unrelated to the Kurdish-led fighters in northern Syria.

Esper said the US withdrawal would be done carefully to protect the troops and to ensure no US equipment was left behind. He declined to say how long that might take.

In a series of tweets on Monday, Trump defended his gamble that pulling US forces out of Syria would not weaken American security and credibility. He took sarcastic swipes at critics who say his Syria withdrawal amounts to a betrayal of the Kurds and plays into the hands of Russia.

“Anyone who wants to assist Syria in protecting the Kurds is good with me, whether it is Russia, China, or Napoleon Bonaparte,” he wrote. “I hope they all do great, we are 7,000 miles away!”

Kurdish fighters announce deal with Syria to deploy troops as Turkish offensive takes tolls

Trump has dug in on his decision to pull out the troops, believing it fulfils a key campaign promise and will be a winning issue in the 2020 election, according to White House officials.

This has effectively ended a five-year effort to partner with Syrian Kurdish and Arab fighters to ensure a lasting defeat of Isis.

Hundreds of Isis supporters escaped a holding camp amid clashes between invading Turkish-led forces and Kurdish fighters, and analysts said an Isis resurgence seemed more likely, just months after Trump declared the extremists defeated.

Trump spoke about the Isis detainees in a call on Monday with Kurdish General Mazloum Kobani. Pence said Mazloum assured the president that Kurdish forces would continue to support the prisons holding Isis fighters.

Will a ‘safe zone’ for returning refugees be set up in northern Syria?

Republican Senate leader Mitch McConnell, normally a staunch Trump supporter, said he was “gravely concerned” by events in Syria and Trump’s response so far.

Withdrawing US forces from Syria “would re-create the very conditions that we have worked hard to destroy and invite the resurgence of Isis”, he said in a statement. “And such a withdrawal would also create a broader power vacuum in Syria that will be exploited by Iran and Russia, a catastrophic outcome for the United States’ strategic interests.”

New Jersey Senator Bob Menendez, the top Democrat on the Senate Foreign Relations Committee, said Trump is weakening America. “To be clear, this administration’s chaotic and haphazard approach to policy by tweet is endangering the lives of US troops and civilians,” Menendez said in a statement.

However, Trump got quick support from Republican Senator Lindsey Graham of South Carolina, who earlier had lambasted his withdrawal decision as “shortsighted”, “irresponsible” and “unnerving to its core”.

Graham said he was asked to join the president and his team for phone calls with the key leaders in the conflict.

“President Trump made it clear to President Erdogan this incursion is widely unpopular in the United States, greatly destabilising to the region, is putting in jeopardy our successes against Isis, and will eventually benefit Iran,” Graham said.

The Kurds have turned to the Syrian government and Russia for military assistance, further complicating the battlefield.

The prospect of enhancing the Syrian government’s position on the battlefield and inviting Russia to get more directly involved is seen by Trump’s critics as a major mistake. But he tweeted that it shouldn’t matter.

“Others may want to come in and fight for one side or the other,” he wrote. “Let them!”

Additional reporting by Catherine Wong