When Donald Trump sat with world leaders in Paris last weekend to marvel at the restored Notre Dame cathedral, armed Islamist fighters in Syria were in jeeps on the road to Damascus finalising the fall of the Assad regime.

In this split screen moment of global news, the US president-elect, seated between the French first couple, still had an eye on the stunning turn of events in the Middle East.

“Syria is a mess, but is not our friend,” he posted the same day on his Truth Social network.

He added: “THE UNITED STATES SHOULD HAVE NOTHING TO DO WITH IT. THIS IS NOT OUR FIGHT. LET IT PLAY OUT. DO NOT GET INVOLVED!”

This post, and another the next day, were a reminder of the president-elect’s powerful mandate to not intervene in foreign policy.

It also raised big questions about what comes next. Given the way the war has drawn in and affected regional and global powers, can Trump really have “nothing to do” with Syria now that President Bashar al-Assad’s government has fallen?

Will Trump pull US troops out?

Does his policy differ drastically from President Biden’s, and if so, what’s the point of the White House doing anything in the five weeks before Trump takes over?

The current administration is involved in a frantic round of diplomacy in response to the fall of Assad and the rise to power of Hayat Tahrir al-Sham (HTS), a Syrian Islamist armed group that the US designates as a terrorist organisation.

I’m writing this onboard Secretary of State Antony Blinken’s plane, as he shuttles between Jordan and Turkey trying to get key Arab and Muslim countries in the region to back a set of conditions Washington is placing on recognising a future Syrian government.

The US says it must be transparent and inclusive, must not be a “base for terrorism”, cannot threaten Syria’s neighbours, and must destroy any chemical and biological weapons stocks.

For Mike Waltz, Trump’s nominee for national security adviser, who has yet to be confirmed, there is one guiding principle to his foreign policy.

“President Trump was elected with an overwhelming mandate to not get the United States dug into any more Middle Eastern wars,” he told Fox News this week.

He went on to list America’s “core interests” there as the Islamic State (IS) group, Israel and “our Gulf Arab allies”.

Waltz’s comments were a neat summary of the Trump view of Syria as a small jigsaw piece in his bigger regional policy puzzle.

His goals are to ensure that remnants of IS remain contained and to see that a future government in Damascus can’t threaten Washington’s most important regional ally, Israel.

Trump is also focused on what he sees as the biggest prize: a historic diplomatic and trade deal to normalise relations between Israel and Saudi Arabia, which he believes would further weaken and humiliate Iran.

The rest, Trump believes, is Syria’s “mess” to work out.

Trump’s rhetoric harkens back to how he talked about Syria during his first term, when he derided the country – which has an extraordinary cultural history dating back millennia – as a land of “sand and death”.

“Donald Trump, himself, I think really wanted very little to do with Syria during his first administration,” said Robert Ford, who served as President Barack Obama’s ambassador to Syria from 2011-14, and who argued within that administration for more American intervention in the form of support for Syrian moderate opposition groups to counter Assad’s brutal suppression of his population.

“But there are other people in his circle who are much more concerned about counterterrorism,” he told the BBC.

The US currently has around 900 troops in Syria east of the Euphrates river and in a 55km (34 miles) “deconfliction” zone bordering Iraq and Jordan.

Their official mission is to counter the IS group, now much degraded in desert camps, and to train and equip the Syrian Democratic Forces (SDF – Kurdish and Arab allies of the US who control the territory).

The SDF also guards camps containing IS fighters and their families.

In practice, the US presence on the ground has also gone beyond this, helping to block a potential weapons transit route for Iran, which used Syria to supply its ally Hezbollah.

Mr Ford, like other analysts, believes that while Trump’s isolationist instincts play well on social media, the realities on the ground and the views of his own team could end up moderating his stance.

That view is echoed by Wa’el Alzayat, a former adviser on Syria at the US Department of State.

“He is bringing on board some serious people to his administration who will be running his Middle East file,” he told the BBC, specifically noting that Senator Marco Rubio, who has been nominated for secretary of state, “is a serious foreign policy player”.

These tensions – between isolationist ideals and regional goals – also came to a head during his first term, when Trump withdrew remaining CIA funding for some “moderate” rebels, and ordered the withdrawal of US forces from northern Syria in 2019.

At the time, Waltz called the move “a strategic mistake” and, fearing an IS resurgence, Trump’s own officials partially rowed back his decision.

Trump also diverged from his non-interventionist ideals by launching 59 cruise missiles at a Syrian airfield, after Assad allegedly ordered a chemical weapons attack that killed scores of civilians in 2017.

He also doubled down on sanctions against Syria’s leadership.

The blurred lines of Trump’s “it’s not our fight” pledge were summed up by Waltz.

“That doesn’t mean he’s not willing to absolutely step in,” he told Fox News.

“President Trump has no problem taking decisive action if the American homeland is threatened in any way.”

Adding to the possibility of tension is another key figure, Tulsi Gabbard, who Trump has nominated as director of national intelligence. The controversial former Democrat-turned-Trump ally met Assad in 2017 on a “fact-finding” trip, and at the time criticised Trump’s policies.

Her nomination is likely to be heavily scrutinised by US senators amid accusations – that she has denied – of being an apologist for Assad and Russia.

Anxiety over the continuing mission in Syria, and a desire to be able to end it, is not exclusive to Trump.

In January, three American soldiers were killed at a US base in Jordan in a drone strike by Iran-backed militias operating in Syria and Iraq, as the Israel-Hamas war in Gaza threatened to spread farther in the region.

This attack and others have continued to raise questions to the Biden administration over US force levels and their exposure in the area.

In fact, many of the outgoing Biden and incoming Trump administrations’ positions on Syria match more than they diverge.

Despite the sharp differences in the tone and rhetoric, both leaders want Damascus run by a government amenable to US interests.

Both Biden and Trump want to build on Iran and Russia’s humiliation in Syria.

Trump’s “this is not our fight, let it play out” is his equivalent of the Biden administration’s “this is a process that needs to be led by Syrians, not by the United States”.

But the “major” difference, and that which raises the most anxiety among Biden supporters, is in Trump’s approach to US forces on the ground and American backing for the SDF, said Bassam Barabandi, a former Syrian diplomat in Washington who helped opposition figures flee the Assad regime.

“Biden has more sympathy, connection, passion towards [the Kurds]. Historically, he was one of the first senators to visit the Kurdish areas [of northern Iraq] after Saddam Hussein’s Kuwait invasion,” he said.

“Trump and his people they don’t care as much… they take it into consideration not to leave their allies out, they get this, [but] the way they implement it is different.”

Mr Barabandi, who said he supports Trump’s non-interventionist rhetoric, thinks the president-elect will pull out US troops “for sure”, but over a gradual timeframe and with a clear plan in place.

“It will not be like Afghanistan, within 24 hours,” he said. “He will say within six months, or whatever time, a deadline for that and for the arrangement of everything.”

Much may revolve around Trump’s discussions with Turkey’s President Recep Tayyip Erdogan, with whom he is thought to have a close relationship.

American backing for the SDF has long been a source of tension with Turkey, which views the People’s Defense Units (YPG) – the Kurdish force that makes up the SDF’s military backbone – as a terrorist organisation.

Since Assad fell, Turkey has been carrying out air strikes to force Kurdish fighters out of strategic areas, including the town of Manbij.

Trump may want to cut a deal with his friend in Ankara that allows him to withdraw US troops and could see Turkey’s hand strengthen further.

But the possibility of Turkish-backed groups taking control of some areas worries many, including Wa’el Alzayat, the former US State Department Syria expert.

“You can’t have different groups running different parts of the country, controlling different resources,” he added.

“There’s either the political process, which I do think the US has a role to play, or something else, and I hope they avoid that latter scenario.”