Washington (CNN) President Donald Trump's unexpected announcement on Thursday that the US would "be coming out of Syria like very soon" is raising concerns among some national security officials who warn that withdrawing now would not only undermine American credibility in the region but prompt a significant escalation to an already devastating conflict.

While Trump has often touted the gains made against ISIS since taking office, his latest comments caught much of his own administration off-guard -- including defense officials who have warned that now is not the time to withdraw from Syria.

"We're knocking the hell out of ISIS. We'll be coming out of Syria like very soon," Trump told supporters outside of Cleveland during a speech that was meant to focus on infrastructure." Let the other people take care of it now."

Several US defense officials have told CNN that the Pentagon has not heard any additional details from the White House since the President's remarks -- adding that the policy hasn't changed and that they are continuing to focus on their fight against ISIS.

One official said the assumption is the President has had a number of briefings saying ISIS is about to be defeated and that many assume Trump was just rhetorically taking it to the next step.

A National Security Council meeting is set for Tuesday to discuss the administration's plan for battling ISIS in Syria, a senior administration official confirmed Saturday.

Any decision by Trump to pull out of Syria would also go against the current military assessment, a fact that left some national security officials concerned about the impact of a withdrawal, another senior administration official told CNN.

Who has the most to lose?

The US maintains about 2,000 US troops in Syria, and primarily backs the Syrian Democratic Forces in the fight against ISIS, a group that is about 50% Arab and 50% Kurdish; however, much of the group's leadership is Kurdish.

The President's apparent desire to exit Syria as soon as possible is likely to raise concerns among US backed groups in the region, particularly the SDF, and could embolden the forces of the Syrian regime, Iran and Turkey, all of which have mostly resisted attacking US allies in Syria due to concerns about US retaliation.

"A lot of what keeps SDF in the field is the other forces can't touch them," according to David Adesnik, the director of research at the Foundation for Defense of Democracies. "Without US support how well will they perform and if they find themselves in a weak position will they cut a deal with regime?"

Recently, the presence of US Forces deterred Russian mercenaries and regime forces from attempting to seize oil fields and other territory controlled by the SDF but without the presence of American troops there is nothing stopping those same forces from attacking again.

A similar dynamic exists in Manbij and At Tanf, where US Forces have deterred Turkish and regime forces from any large scale attacks.

The US is also helping SDF forces secure Syria's border with Iraq as ISIS still maintains a presence in the area but that job becomes much more difficult without American assistance.

A US withdraw could help ISIS

If the US were to withdraw, the de facto spheres of influence that have spared eastern Syria the same kind of fighting and bloodshed that the civil war has brought to the west would likely collapse, inviting a major escalation in the conflict.

That chaos could be exploited by ISIS which has already benefited from Turkey's actions in northern Syria.

Earlier this month, the US warned that ISIS has begun reconstituting in some areas of Syria because a Turkish military offensive against a northern city has pulled the US' Kurdish allies away from the fight against the terrorist group.

"We are very concerned about the effect fighting there has had on our defeat ISIS efforts and would like to see an end to the hostilities before ISIS has the opportunity to regroup in eastern Syria," said Pentagon spokesman US Army Col. Rob Manning, discussing the Turkish offensive against Afrin.

The State Department went a step farther, saying that ISIS has already begun to rebuild in places.

"The fighting in western Syria over the last two months, including in Afrin, has distracted from the defeat ISIS campaign and provided opportunity for ISIS to begin reconstituting in some areas," State Department spokeswoman Heather Nauert said last week.

US officials have been warning for weeks that the Turkish military campaign against Kurdish forces in Afrin, launched January 20, could undermine the fight against ISIS, as Kurdish fighters helping the US battle the terrorist group began leaving to help their compatriots there. But the Turks see the US' Kurdish allies as terrorists and have strongly pushed back against US claims that their involvement has a negative impact on the campaign against ISIS.

"The claim that the operation conducted against terrorists in Afrin would endanger the combat against DAESH is completely groundless," said a statement from the Turkish Foreign Ministry last week, using the Arabic name for ISIS. "The approach that actually undermines the combat against terrorism in Syria is the use of one terrorist organization against another."

In a January speech laying out the Trump administration's policy on Syria, then Secretary of State Rex Tillerson said the US would remain in Syria until the group is routed. "The United States will maintain a military presence in Syria focused on ensuring ISIS cannot re-emerge," Tillerson said at Stanford University. "The fight against ISIS is not over."

Russia, Iran and Turkey stand to benefit

The involvement of both US and Russian forces in Syria has complicated the conflict, leaving the countries conduct a delicate dance in order to avoid directly attacking one another.

That hasn't always worked, though.

Several Russians hired as paramilitary contractors to fight with pro-Assad forces were killed by US air strikes in February , according to friends and family of those killed. The US and Russia have maintained "deconfliction" communications channels to avoid direct combat, but the lines do not prevent all conflicts.

A US withdrawal would create a vacuum in the area, similar to what happened after soldiers left Iraq, and most foreign policy experts agree that void would likely be filled by Russia.

Angela Stent, director of the Center for Eurasian, Russian and East European Studies at Georgetown University, told CNN on Friday that "if the US were to withdraw, it seems to me the Russians would have a free hand" in Syria and the forces "fighting Assad would be weakened."

"I do wonder if that is something the President thought about when he made that announcement," Stent said, noting that any departure would elevate Russia's status to make it "the main power broker in that area."

Additionally, Stent said, a US withdrawal would help Iran, a country whose forces are fighting alongside Russians in Syria.

If the US were to leave its base located at the At Tanf garrison in southeastern Syria, Iran would be able to secure its overland route from Damascus to Tehran, further securing its regional influence.

Given Trump has routinely advocated for tougher policies on Iran, the US would be "cutting off our nose to spite our face" by withdrawing from Syria, Adesnik said.

Along with Russia, Iran and the Syrian regime could also benefit from the economic advantages of seizing oilfields currently controlled by US-backed allies.

The regime lost roughly 90% of its oil production when the civil war began, according to Adesnik.