WASHINGTON — President Donald Trump said on Tuesday he wants American troops to "get out" of Syria, even as some of his top officials stressed the need to stay for the long term.

Trump’s remarks follow comments last week when he vowed US forces would soon quit Syria, a position at odds with establishment doctrine that a premature pullout from the war-torn nation would have far-reaching negative consequences.

"Our primary mission in terms of Syria was getting rid of ISIS," Trump said, using an acronym for the Islamic State group.

"We’ve almost completed that task. And we’ll be making a decision very quickly in coordination with others in the area as to what we’ll do."

The president added: "I want to get out, I want to bring our troops back home. I want to start rebuilding our nation."

But at the same time Trump was speaking at a news conference with Baltic leaders, the top commander for the war against IS signaled different views.

General Joe Votel, who leads the military’s Central Command, suggested the US should play a long-term role in Syria in terms of stabilising the areas freed from IS occupation.

"The hard part I think is in front of us and that is stabilising these areas, consolidating our gains, getting people back into their homes, addressing the long term issues of reconstruction and other things that will have to be done," Votel said at the US Institute of Peace in Washington.

"Of course there is a military role in this, certainly in the stabilization phase," he added.

And Brett McGurk, the US envoy to the coalition against IS, stressed the fight against the jihadists was not over.

Trump recently fired Rex Tillerson as secretary of state and axed HR McMaster as national security adviser, replacing him with hardline Fox News pundit and former UN ambassador John Bolton.

The "America First" president’s lines about defeating IS draw cheers from his base, as do promises to bring troops home, and he has shown a growing eagerness to take counter-orthodox views on a range of issues including trade and US border security.

But Charles Lister, a senior fellow and director of the Extremism and Counterterrorism Program at the Middle East Institute, said Trump has not grasped the complexities of Syria’s knotted conflict.

"Once he’s sat down and talked through all of the central implications and the realities on the ground and the threats we face by leaving... he might be turned around again," Lister said.

Saudi money

Officials say 98 per cent of the vast regions IS once held in Syria and Iraq have been liberated, but the group maintains a presence along the Euphrates River Valley in eastern Syria and the military is wary of the fighters mounting a long-term insurgency.

"We are ahead of where we thought we would be at this time, but we are not finished and we have to work through some very difficult issues as we speak," McGurk said.

Trump said he would consult with allies and suggested that Saudi Arabia might pay the bill for US troops being there.

"Saudi Arabia is very interested in our decision. And I said, well, you know, you want us to stay maybe you’ll have to pay," he said.

In another sign of Trump’s waning interest in Syria, The Wall Street Journal has reported that he had placed on hold $200 million in US funding to help stabilize areas of eastern Syria recaptured from IS.

"The president has been very clear to us that everything we’re doing has to constantly be reviewed and looked at," McGurk said.

"On this $200 million, we’re looking at where can it be spent most effectively."

Trump’s apparent willingness to step away from the chaos of Syria runs counter to a new US strategy announced in January by Tillerson prior to his sacking.

Tillerson argued US forces must remain engaged in Syria to prevent IS and al-Qaeda from returning and to deny Iran a chance to "further strengthen its position in Syria."

Alireza Nader, an international policy analyst at the Rand Corporation, said a decision to pull out of Syria would be "great news" for leaders in Iran, leaving the Islamic Republic scope to expand its influence across Syria.

"This really would contradict President Trup’s goal of countering Iran in the Middle East," Nader said.

"If the US wants to counter Iran in the region, it has to stay in Syria." — AFP