WASHINGTON (Reuters) - President Donald Trump signed a revised executive order on Monday banning citizens from six Muslim-majority nations from traveling to the United States but removing Iraq from the list, after his controversial first attempt was blocked in the courts.

The new order, which takes effect on March 16, keeps a 90-day ban on travel to the United States by citizens of Iran, Libya, Syria, Somalia, Sudan and Yemen. It applies only to new visa applicants, meaning some 60,000 people whose visas were revoked under the previous order will now be permitted to enter.

Immigration advocates said the new ban still discriminated against Muslims and failed to address some of their concerns with the previous order. Legal experts said it would, however, be harder to challenge because it affects fewer people living in the United States and allows more exemptions to protect them.

Trump, who first proposed a temporary travel ban on Muslims during his presidential campaign last year, had said his original Jan. 27 executive order was a national security measure meant to head off attacks by Islamist militants.

It sparked chaos and protests at airports, where visa holders were detained and later deported back to their home countries. It also drew criticism from targeted countries, Western allies and some of America’s leading corporations before a U.S. judge suspended it on Feb. 3.

“As threats to our security continue to evolve and change, common sense dictates that we continually re-evaluate and reassess the systems we rely upon to protect our country,” Secretary of State Rex Tillerson told reporters after Trump signed the new order.

PELOSI SAYS BAN STILL ‘IMMORAL’

Democrats, a minority in Congress, quickly signaled fierce opposition to what they called a discriminatory ban.

“The Trump administration’s repackaging has done nothing to change the immoral, unconstitutional and dangerous goals of their Muslim and refugee ban,” House of Representatives Democratic leader Nancy Pelosi said in a statement.

Farhana Khera, executive director of Muslim Advocates, a civil rights group in Washington, said the Trump administration had “doubled down on anti-Muslim bigotry.”

She told reporters on a conference call: “It’s crystal clear this is a Muslim ban.”

But some Republicans who had been critical of Trump’s original order were more positive on the new one.

Bob Corker, chairman of the Senate Foreign Relations Committee, said he was “very encouraged” by the approach and pleased that Iraq was removed from the list.

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Iraq was taken off the banned list because the Iraqi government has imposed new vetting procedures, such as heightened visa screening and data sharing, and because of its work with the United States in countering Islamic State militants, a senior White House official said.

Trump’s original ban resulted in more than two dozen lawsuits in U.S. courts. The Justice Department estimated 60,000 people had their visas revoked by the first order but senior administration officials said on Monday those visas were now valid again for entry into the United States.

“By rescinding his earlier executive order, President Trump makes one thing perfectly clear: his original travel ban was indefensible - legally, constitutionally and morally,” said Attorney General Bob Ferguson of Washington state, which succeeded in having the previous ban suspended.

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His office will likely decide this week on whether to proceed with litigation over the new order, he said.

Senate Democratic leader Chuck Schumer said he expected the revised order to have the same uphill battle in the courts as the original version.

“A watered down ban is still a ban,” he said in a statement. “Despite the administration’s changes, this dangerous executive order makes us less safe, not more, it is mean-spirited, and un-American. It must be repealed.”

HARDER TO CHALLENGE

The fact the ban affects fewer people already in the United States means it will be more difficult for opponents to find plaintiffs who have been harmed by the order and thus have legal standing to challenge it, legal experts said.

The revised order expressly makes waivers possible for a foreign national seeking to enter the United States to visit a spouse, child or parent who is a U.S. citizen, or for “significant business or professional obligations.”

“They dotted their i’s and crossed their t’s in trying to anticipate what litigation might result,” said Stephen Yale-Loehr, a Cornell Law School professor.

The revised order means that tens of thousands of legal permanent U.S. residents - or green card holders - from the listed countries will no longer be affected.

The original order barred travelers from the seven nations from entering for 90 days and all refugees for 120 days. Refugees from Syria were to be banned indefinitely but under the new order they are not given separate treatment.

Refugees “in transit” and already approved would be able to travel to the United States under the new order.

Defense Secretary Jim Mattis, who along with several other senior Cabinet members had lobbied for Iraq’s removal from the list of banned countries, was consulted on the new order and the updated version “does reflect his inputs,” Pentagon spokesman Captain Jeff Davis said.

Thousands of Iraqis have fought alongside U.S. troops for years or worked as translators since the U.S.-led invasion in 2003. Many have resettled in the United States after being threatened for working with U.S. troops.