Customs and Border Protection is notifying airlines about passengers whose visas had been canceled or legal residents scheduled to fly back to the USA, and the airlines are being told to keep them off those flights.
Green card holders - legal permanent residents of the us - are also included in the ban, according to a senior Trump administration official.
The official says there's an exemption for immigrants and legal permanent residents whose entry is in the US national interest, but it's unclear how that exemption will be applied.
One of the two Iraqi refugees who were detained at the airport on Friday has been released from custody.
The two Iraqis who were detained at JFK Airport have filed lawsuits against Trump, and one of them has been released.
Hameed Khalid Darweesh and Haider Sameer Abdulkhaleq Alshawi, both from Iraq, were detained at Kennedy Airport on Friday night, according to papers filed in the Eastern District of NY.
The initial lawsuit, filed this morning, asks the court to agree to treat all immigrants being detained under the ban as a class - and to issue an injunction preventing Customs and Border Protection agents from detaining anyone exclusively on the basis of Trump's executive order.
It even extends to green card holders who are granted authorisation to live and work in the U.S., according to a Department of Homeland Security spokeswoman.
Darweesh worked as an interpreter for the U.S. Army when it invaded Iraq in 2003.
After Darweesh was released, he spoke to reporters who were likely expecting some hard feelings toward Trump. While she was en route to the country, Trump's executive order was signed.
One of the countries on the immigration black list is Somalia, causing confusion and fear among Minnesota's large and growing Somali population.
"They're being persecuted", Darweesh's lawyer, Doss, told CNN. "And he put his life on the line". An unknown number of refugees and immigrants were detained at US airports on Friday and Saturday as legal advocates rushed to their aid.
On Friday, he signed an executive order barring all refugees from entering the United States for 120 days and placing an indefinite ban on those from Syria. It also calls for the complete suspension of Syrian refugees for an indefinite period. It shrinks the overall refugee program by more than half.
Trump said Christian refugees would be allowed into the country, who he said are targeted above all others. A Sudanese student at Stanford University was blocked for hours from returning to California.
"Mr. President, look around, this is America", said U.S. Rep. Nydia Velzquez (D-NY) during a press conference.