(CNN) Syrian President Bashar al-Assad rejected the idea advanced by US President Donald Trump of creating safe zones for refugees and displaced people in Syria.

"Safe zones for the Syrians could only happen when you have stability and security, where you don't have terrorists, where you don't have flow and support of those terrorists by the neighboring countries or by Western countries... It's much more viable, much more practical and less costly to have stability than to create safe zones. It's not a realistic idea at all," Assad told Yahoo News in an interview published Friday by state-run SANA.

Safe zones are meant to be areas where civilians can live without fear of being targeted by any party, protected by the international community. The Syrian government has persistently and broadly branded as terrorists those fighting to topple Assad.

Trump has said that he would "absolutely do safe zones in Syria" for refugees fleeing violence within their country, which has been devastated by years of civil war.

Stemming refugee tide

In an interview last month with ABC, Trump said Germany and other European countries had made a mistake by allowing millions of refugees across their borders.

"I don't want that to happen here," he said, without elaborating on his plan for safe zones in Syria.

Trump also broached the idea in November 2015 as a candidate, when he proposed building "a big beautiful safe zone, and you have whatever it is so people can live, and they'll be happier."

The Trump administration sees safe zones as the way to stem and even reverse the migration of Syrians to Europe and elsewhere.

But how they would work?

For starters, safe zones would need to be protected both by ground forces and the imposition of a no-fly zone, both of which would require detailed planning and substantial resources.

Beyond that, several issues loom. Would the administration seek the creation of safe zones through the United Nations, by agreement with other governments (principally Russia and Syria), or unilaterally? How big and where would they be? Would they promote the division of Syria? Then, there is the issue of cost.

For all these and other reasons, the Obama administration shied away from supporting safe zones, despite considerable lobbying from Turkey, where some 2.8 million Syrian refugees are registered.

Travel ban 'an American issue'

In his interview with Yahoo News, the Syrian President described Trump's travel ban on seven Muslim-majority countries, including Syria, as "an American issue," though he agreed that some refugees are "definitely" aligned with terrorists.

A federal appeals court panel late Thursday refused to restore the travel ban , which the courts suspended last week. Trump vowed to fight for the ban in court, calling it paramount to nation security.

Syrian President Bashar al-Assad in picture released by the official Syrian Arab News Agency (SANA) on February 8.

Asked by Yahoo News if some refugees are aligned with terrorists, Assad said, "Definitely. You can find it on the net; the same picture that you saw... in some instances, those terrorists in Syria, holding the machine gun or killing people, they are peaceful refugees in Europe or in the West in general. Yeah, that's true."

Assad also said US-Russian cooperation was "essential" in the fight against terror. The Syrian President said he would "welcome" US troops in Syria if their intent to fight terror was "genuine."

"We invited the Russians, and the Russians were genuine regarding this issue. If the Americans are genuine, of course they are welcome, like any other country that wants to defeat and to fight with the terrorists. Of course, with no hesitation we can say that," Assad said, according to an interview transcript.

"The position of President Trump since he started his campaign for presidency till this moment is that the priority is to fight terrorism, and we agree about this priority, that's our position in Syria, the priority is to fight terrorism, and that's what I meant by promising," he said.

Asked what message he would convey to Trump, Assad said, "We have one stand, one position toward what's happening in Syria, and it's about fighting terrorism."

So far, Assad said, he has not had any communication with the Trump administration.