On Monday morning––and weeks later than expected––President Donald Trump signed a new version of his travel ban, blocking nationals of six majority-Muslim countries from entering the United States. And on a call with reporters before the signing, senior administration officials hinted that more countries could be added to the ban in several months.

The new ban is different from the old one in a few key ways. First, it only includes six countries: Yemen, Somalia, Syria, Libya, Sudan, and Iran. It won’t block travel from Iraq. Administration officials said that’s because the Iraqi government agreed to share more information about travelers with the U.S. government and because it agreed to repatriate Iraqis who the U.S. government ordered deported.

The ban will go into effect on March 16 at 12:01 a.m., according to officials, and it won’t apply to people from the six countries who have valid visas at that point. The ban will be in place for 90 days.

Despite the changes to the ban, its critics say it still unconstitutionally targets Muslims, and that it doesn’t have any national security justification.

“You can’t blueline-edit hate and bigotry this way,” said Abed Ayoub, national legal and policy director at the American-Arab Anti-Discrimination Committee. “You cannot remove certain language or remove a country and think it takes away from it being a Muslim ban.”

And despite the changes, the new ban will likely draw legal challenges. The travel ban will likely kick off more legal challenges. Omar Jadwat, who heads the ACLU’s Immigrants’ Rights Project, said in a statement that the ban would still have constitutional problems.

“The only way to actually fix the Muslim ban is not to have a Muslim ban,” he said. “Instead, President Trump has recommitted himself to religious discrimination, and he can expect continued disapproval from both the courts and the people.”

“What's more, the changes the Trump administration has made, and everything we've learned since the original ban rolled out, completely undermine the bogus national security justifications the president has tried to hide behind and only strengthen the case against his unconstitutional executive orders,” he added.

Speaker of the House Paul Ryan praised the move.

“The revised executive order advances our shared goal of protecting the homeland,” he said in a statement. “I commend the administration and Secretary Kelly in particular for their hard work on this measure to improve our vetting standards. We will continue to work with President Trump to keep our country safe.”

Trump’s first effort at a travel ban came on Jan. 27, when he signed an order blocking people from seven countries, as well as refugees. The order caused chaos at airports, and a federal judge blocked its enforcement about a week later. Since then, Trump officials have been working to find a new way to ban travelers from those countries without getting in legal trouble.

Officials said the president will also ask the Department of Homeland Security and the State Department to assess whether any other countries should be added to a future travel ban. The officials didn’t say if the White House has immediate plans for another ban to be implemented after the 90 days are up.

The executive order will also suspend the Refugee Admissions Program for 120 days, according to officials. And it will slash the number of refugees accepted into the U.S. through that program this year––cutting the number in half, from 110,000 to 50,000.

Administration officials said the executive order would say the FBI is currently investigating 300 people who entered the U.S. as refugees for suspected connections to terrorism. But officials on the call didn’t say what countries those 300 people are from, how long they have been in the U.S., and whether any of them have become naturalized citizens. A DOJ official on the call declined to provide reporters with any additional details about those 300 people being investigated.

Ayoub said the administration’s use of that figure is troubling.

“To use these statistics in an attempt to brush the whole refugee community as terrorists or criminals is problematic, and it supports the notion that this ban is not about national security,” he told The Daily Beast. “This ban is about Islamophobia and xenophobia, and there’s an anti-Arab sentiment to this ban as well and that’s being exhibited by using such a low number to paint the whole refugee community in this fashion.”