"We will be leaving at a proper pace while at the same time continuing to fight ISIS and doing all else that is prudent and necessary!" Trump tweeted.

The president has come under withering pressure both at home and in allied capitals after previous statements indicating that he considered the IS group vanquished and that he wanted US troops out of Syria imminently.

Trump's new statement follows a trip by his national security adviser John Bolton to Israel in which he told Prime Minister Benjamin Netanyahu on Sunday that withdrawal would not happen before "ISIS is defeated and not able to revive itself."

In a call, Trump and French President Emmanuel Macron spoke of "the commitment of the United States and France to the destruction of ISIS as well as plans for a strong, deliberate, and coordinated withdrawal of US troops from Syria," the White House said.

"They reiterated that any further use of chemical weapons in Syria must not be tolerated."

Secretary of State Mike Pompeo said he had spoken with French officials. "We'll make sure we address the concerns that they have. Everyone understands what the United States is doing," he told reporters as he headed on a Middle East visit.

The reassurances followed a diplomatic storm caused by Trump's surprise announcement in December that appeared to signal a rapid withdrawal from Syria, where US special forces play an important role in supporting local forces fighting IS.

"We've won against ISIS," he said at the time. "We've beaten them and we've beaten them badly. We've taken back the land. And now it's time for our troops to come back home."

Allies like Britain and France warned that IS was not defeated. Questions were also raised over the fate of Kurdish groups that have done much of the fighting alongside the United States in Syria, but now fear attacks from Turkey.

The initial pullout promise also sparked outspoken opposition from within Trump's Republican party and the resignation of respected defense secretary James Mattis.

In Monday's statement, Trump complained that media coverage had skewed his original words, saying that his latest position on Syria was "no different from my original statements."

Currently, about 2,000 US forces are in the Syria, which is in the grips of a complex civil war. Most of the US soldiers are there to train local forces fighting the hardcore-Islamist IS.

"We will continue to work with the coalition and regional partners toward an enduring defeat of ISIS," Commander Sean Robertson, a Pentagon spokesman, told AFP.