President Donald Trump s executive order freezing the United States refugee resettlement program, barring Syrian refugees indefinitely and temporarily restricting immigration from unnamed countries is already resulting in families being stopped at airports .

But the order is also notable for its exclusion of a provision, which appeared in an earlier draft of the order, that would have created a process for establishing so-called safe zones in Syria.

That clause would have instructed the secretary of defense to draft a plan within 90 days to create safe zones to protect vulnerable Syrian populations, according to a copy of the draft published by The Huffington Post on Wednesday.

The decision to omit the safe zones proposal allows the Trump administration to avoid, at least temporarily, the complex questions that such a policy would raise. Creating and protecting safe zones could increase American military intervention in Syria, and pose a number of political and logistical problems regarding its implementation.

Both Republican and Democratic officials have at times advocated for implementing safe zones in Syria. Former Secretary of State Hillary Clinton made safe zones part of her foreign policy platform during her 2016 presidential campaign, and prominent GOP figures like Sens. Marco Rubio (Fla.), Lindsey Graham (S.C.) and John McCain (Ariz.) have all advocated for the policy .

German Chancellor Angela Merkel also supported potential safe zones along the Turkey-Syria border, and has discussed the idea of havens for displaced Yazidis in northern Iraq. Turkey has previously backed the policy as well, and already controls a strip of land in Syria along its border that has become something of a de facto safe zone for internally displaced people.