(CNN) If President Donald Trump makes good on his promise to get out of Syria "very soon," one of the biggest winners will be Russian President Vladimir Putin and the Russian government.

Although the Kremlin has tried to cast its involvement in Syria as primarily an air campaign, there are extensive Russian boots on the ground through military contractors, and a US withdrawal would make their job of combating forces hostile to Syrian President Bashar al-Assad considerably easier.

Trump made the unexpected announcement on Thursday during an event in Ohio that was meant to focus on infrastructure reform . Trump, though, barely focused on infrastructure and instead held court in a campaign-style speech where he touched on everything from war and peace to the ratings of a new television sitcom.

"We're knocking the hell out of ISIS. We'll be coming out of Syria like very soon," Trump told supporters outside of Cleveland. "Let the other people take care of it now."

The comment caught much of the Trump administration off guard , leaving officials inside the Pentagon -- including some who had worked directly on the campaign to combat ISIS in Syria -- scratching their heads. It also contradicted a long-held Trump pledge to never telegraph future military decision.

One defense official told CNN after the speech that it was unclear what the President meant. Even almost 24 hours after the remarks, a National Security Council spokesperson responded to questions about the comment by simply stating: "The President's comments speak for themselves."

And even those close to Trump were confounded. A senior administration official told CNN on Friday that some aides to the President were surprised by his remark.

"We are still trying to figure out what he meant about Syria yesterday," the official said.

Critical time in Syria

The uncertainty around the President's plans on Syria come at a critical time for the National Security Council. White House officials are bracing for staffing changes at the council with the arrival of new national security adviser John Bolton. It's a "guessing game" as to which officials will be out the door, an official said.

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.

The Pentagon's current assessment is that now is not the time to consider withdrawal, citing numerous challenges in Syria. One issue is that the US leaving would create a vacuum in the area, similar to what happened after soldiers left Iraq.

Additionally, the official noted unresolved questions, like what to do with some 400 foreign ISIS fighters being held by the US-backed Syrian Democratic Forces and a decision about whether the United States could accept a future where Assad remains in power.

And most foreign policy experts believe that vacuum would likely be further 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."

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

"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."

The involvement of both US and Russian forces in Syria has complicated the conflict, leaving the countries to do 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.

The conflict has also cost US lives. On Friday, a US official with knowledge of the initial reports from the battlefield told CNN that at least one US solider was killed in an improvised explosive device attack in the Manbij area of Syria on Thursday.

US-Russia tension

Trump's suggestion that the United States is in the process of withdrawing from Syria comes amid simmering tensions between the United States and Russia.

After the United States expelled 60 Russian diplomats and closed a consulate in Seattle, Russia responded by expelling the same number of foreign service officers and closing the consulate in St. Petersburg.

Tensions between the two countries have boiled throughout the Trump administration, despite the fact that the President has avoided directly attacking Russia and dismissed most questions about Russia as nothing more than an attempt to discredit his 2016 election as special counsel Robert Mueller investigates Russian meddling in the election and possible collusion with the Trump campaign.

While Trump has personally remained silent, his administration has confronted Russia . The administration unveiled new sanctions on Russia earlier this year, punishing individuals indicted by Mueller in February in a sweeping new effort to come down on Moscow for its interference in the 2016 election.

Ever since taking office, Trump has been in the middle of a tug-of-war between his desire to appear like a strongman president and his campaign promise to withdraw the United States from foreign conflicts.

While Trump has frequently touted the gains made against ISIS since taking office, he repeatedly slammed President George W. Bush's handling of the Iraq war during the 2016 campaign.

"General George Patton, General Douglas MacArthur are spinning in their graves at the stupidity of what we're doing in the Middle East," Trump said during a presidential debate to slam Hillary Clinton, a former secretary of state.

As president, however, Trump has only maintained foreign involvement in wars. Last year, for example, Trump vowed the US will "fight to win" in Afghanistan, extending a 16-year war that he once proposed fully ending.