WASHINGTON – President Donald Trump’s order banning refugees from seven Muslim majority nations from the U.S. also includes legal U.S. residents from those countries, prompting a warning Saturday from a leader of an immigration group that those green card holders should not leave the U.S. because they may not be allowed to return.

“We are saying, people should not be traveling until we get much more clarity about what this administration is doing,” Marielena Hincapie, the executive director of the National Immigration Law Center, told the Chicago Sun-Times.

The Center, along with the American Civil Liberties Union Foundation and other legal groups, filed a lawsuit on Saturday on behalf of two Iraqi men with immigrant visas detained at John F. Kennedy Airport in New York.

The two were blocked from entering the U.S. after Trump signed an executive order on Friday barring people from Syria, Iran, Iraq, Yemen, Sudan, Somalia and Libya from entering the U.S. for 90 days.

Trump’s order includes more – it will prevent green card holders from those nations traveling outside the U.S. from entry back into the U.S. A green card grants the holder the legal right to be a permanent resident of the U.S.

At a White House briefing on Saturday, reporters were told green card holders from the seven listed nations who are currently outside the U.S “will need a case by case waiver to return to the United States,” according to an official.

Hincapie said with little advance notice and no written public guidelines with details on how to carry out Trump’s order, the situation is “truly chaotic in addition to being unconstitutional.”

Hincapie said the lawsuit may be amended to take in green card holders from the seven nations.