Donald Trump stressed that "not one drop of American blood" was shed.

US President Donald Trump Thursday welcomed the temporary ceasefire in northern Syria and said he allowed Turkish and Kurdish forces to clash in deadly battle because they were like children who needed to fight each other.

"It was unconventional what I did. I said they're going to have to fight a little while," Trump told a rally of supporters in Dallas, Texas.

"Like two kids in a lot, you have got to let them fight and then you pull them apart.

"They fought for a few days and it was pretty vicious."

Trump triggered the week-long Turkish offensive against the Kurds by withdrawing US troops from northeast Syria.

More than 500 people have been killed, including dozens of civilians, mostly on the Kurdish side, and 300,000 civilians have been displaced within Syria, according to the Syrian Observatory for Human Rights war monitor.

Trump stressed that "not one drop of American blood" was shed.

Earlier he hailed the announcement that Turkey had agreed to suspend its offensive, calling it a "great day" for the Turks and the Kurds.

"We have a five-day ceasefire," Trump told reporters, after Vice President Mike Pence said Ankara had agreed to suspend its military operation, and end it entirely once Kurdish fighters withdraw from a safe zone along the Turkey-Syria border.

"It's a great day for the United States," the president said in Fort Worth, Texas, ahead of a re-election rally.

"It's a great day for Turkey," Trump said. "It's a great day for the Kurds. It's a great day for civilization."

"This is a situation where everybody's happy," he declared.

'Obscene and ignorant'

Trump also heaped praise on Turkish President Recep Tayyip Erdogan and said it would no longer be necessary to impose US sanctions on Turkey.

"He's a hell of a leader," Trump said. "He did the right thing."

Trump has come under bipartisan fire in Washington for abruptly pulling US troops in Syria near the Turkish border, paving the way for Ankara's operation against the Kurds, who have been US allies in the fight against the Islamic State group.

Brett McGurk, former presidential special envoy for the anti-IS coalition, described Trump's remarks about "two kids" fighting as "obscene and ignorant."

"200k innocent people displaced. Hundreds dead. Credible reports of war crimes. ISIS prisoners escaping. US evacuating and bombing its own positions or handing them to Russia. Two kids in a lot?" he said on Twitter.

The agreement struck by Pence also left some lawmakers in Washington, including in Trump's Republican Party, unimpressed.

"Other than giving Kurds a chance to leave so they don't get slaughtered, it doesn't sound like a change of any of the other dynamics I'm concerned about," Senator Marco Rubio, a Republican on the Senate Foreign Relations Committee, told reporters.

Senator Lindsey Graham, who hours earlier unveiled legislation that would impose sharp sanctions on Turkey, said that while he was encouraged by the recent developments between Pence and Erdogan, "we're going to keep working" to get the sanctions bill to the Senate floor for a vote.

Turkey and Syrian rebel proxies began an offensive in northern Syria last week against Kurdish fighters who Ankara brands terrorists, despite international concern over regional stability and civilian deaths.

Ankara considers Syrian Kurdish YPG militants to be an extension of the outlawed Kurdistan Workers' Party (PKK) -- a group that has fought a bloody insurgency inside Turkey for 35 years.