The US President Donald Trump made clear his intention to undo the legacy of Barack Obama and offer a different Middle East policy.

No better place to start than Syria, especially considering it was the most prominent stain on Obama's foreign policy record where he was reluctant to intervene in two watershed moments: in 2013, when a no-fly zone was a military option to cripple the Syrian regime's air force; and in 2015, when a safe zone was meant to shelter refugees in northern Syria.

While Obama did not act because he was considering the possible military outcome of that decision, Trump is now limiting the safe zone debate to a US homeland security perspective.

Trump's thinking

In a campaign speech in Knoxville, Tennessee, in November 2015, then candidate Trump laid out what can be interpreted as a "real estate" approach to protecting Syrian civilians.

He suggested to "take a big swatch of land" for "the right price" and build "a big beautiful safe zone" that will make Syrian refugees "happier".

Trump's thinking on Syria was motivated by keeping Syrian refugees, and the risks they allegedly pose, away from the United States and Europe. He is now following through on his campaign promise.

That link between establishing a safe zone and suspending the admission of Syrian refugees to the US was evident in the draft executive order dedicated to prevent "foreign terrorists" from entering the country. Ultimately that provision was not included in the final version of the executive order released on January 27. However, Trump remains adamant about advancing this issue.

On January 29, he officially requested Saudi support for implementing safe zones that help alleviate the burden of "those who are suffering". Obviously, one cannot ignore the stark moral contradiction between considering Syrian refugees as "detrimental to the interests of the United States" and intervening in their country to help them.

The Trump administration should not expect the safe zone to run on cruise control without heavy US involvement. Past experiences in Iraq and Bosnia tell us that US interest in enforcing such a zone will run out of steam over time and regional players will probably fill the vacuum and further feed the conflict.

Given the military dynamics in Syria, a safe zone is not achievable without a no-fly zone and it requires significant resources as well as regional buy-in.

The US military has been and remains reluctant to take part in such a plan that carries risks of confrontation by transforming its role from defeating the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) to policing a safe zone.

The Pentagon estimated that it will take between 15,000 and 30,000 US troops to secure a safe zone in Syria with a cost of at least $1bn a month.

The Trump administration should not expect the safe zone to run on cruise control without heavy US involvement. Past experiences in Iraq and Bosnia tell us that US interest in enforcing such a zone will run out of steam over time and regional players will probably fill in the vacuum and further feed the conflict.

Changing regional conditions

In the regional context, the safe zone can indeed be a game changer. A lot has happened in Syria since the last time that plan was seriously considered in Washington.

Russia became a force to reckon with since its intervention in September 2015, the Turkish incursion in northern Syria began in August 2016 and Aleppo fell last December into the hands of the Syrian regime.

Turkey is currently shaping a de facto safe zone between Afrin and Jarablus along its border with Syria, part of a demographic battle with the People's Protection Units (YPG) that represents Syrian Kurdish forces.

Turkish troops are struggling to defeat ISIL in al-Bab while the US forces are mediating between Turkey and the YPG to decide who will ultimately take control of Manbij. The mechanism of implementing the safe zone will distract both Turkey and the YPG from their separate fight against ISIL.

It is also useful to remember that the safe-zone proposal between Afrin and Kobane failed in 2015 because the US wanted to exclude ISIL only, while Turkey wanted a zone that also excluded YPG and the Syrian regime.

Simply put, in return for endorsing a safe zone, Turkey wants Washington to cease its support for the YPG, a programme that is widely endorsed across the US bureaucracy. A rash decision to establish a safe zone in the current political environment will hasten the looming confrontation between Turkey and YPG.

As recent as December 2016, Trump said: "I will get the Gulf states to give us lots of money, and we'll build and help build safe zones in Syria".

For Saudi Arabia to accept investing in a safe zone considering its current budget constraints, it will probably need a US commitment to deter Iran and its allies. However, Saudi Arabia's influence in Syria has weakened in recent months, a safe zone might offer the unique opportunity for a comeback.

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Russia and Iran share similar scepticism towards the safe zone idea. Moscow will seek to maintain leeway in deciding what happens in Syria while Tehran will try to strengthen its control on the remaining parts of the country.

Many are betting that the Trump approach could lead to disagreement between Moscow and Tehran over Syria, which might be true about tactics but not on the overall strategy.

A safe zone must be part of a Syria policy as well as the larger picture of how the Trump administration sees its role in the Middle East. It is an end point, not the starting point for that policy debate.

What is disconcerting, though, is the White House's interventionist impulse. It is unclear to what extent the Pentagon can continue to play a check-and-balance role when the joint chiefs of staff have been relegated in the structure of the National Security Council.

The safe zone policy will probably be a by-product of the tug of war inside the Trump administration.

Joe Macaron is a policy analyst at the Arab Center Washington DC.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.