The White House unveiled its new executive order Monday re-instituting a ban on travel from certain Muslim-majority nations.

The order, announced by senior administration officials but, unlike the first, not signed in a public ceremony by President Donald Trump, restores the original order's 120-day suspension of the U.S. refugee program and its restrictions on entry by citizens of six other nations: Iran, Libya, Somalia, Sudan, Syria and Yemen.

In a departure from the original order signed Jan. 27, the new travel restrictions exempt Iraqi citizens, as well as legal permanent residents and visa holders. The order also does not explicitly bar Syrian refugees, who had been singled out and banned indefinitely under the original order, and it does not prioritize certain religious minorities.

The travel restrictions for the six named countries are effective for 90 days, and senior administration officials said that nations may be added to or removed from the list based on U.S. assessments of their screening procedures for travelers and their cooperation with security standards.

The original order, which came with little warning and set off widespread confusion and mass protests at international airports, has been frozen by a federal court since Feb. 3 pending a legal challenge by civil rights groups.

Although Trump and administration lawyers said that any delay in implementing the restrictions imperiled national security and, as the president said last month, would allow "a lot of bad people" into the country, the new provisions will not take effect until March 16.

Top officials, reiterating prior statements about the original order, said the restrictions amount to a pause to allow authorities to examine potential vulnerabilities in the immigration system and emphasized that the measures are lawful.

"The president is exercising his rightful authority to keep our people safe," Secretary of State Rex Tillerson said in prepared remarks Monday. "As threats to our security continue to evolve and change common sense dictates that we continue to re-evaluate the systems we rely upon to protect our country."

The theme of constitutionality was echoed by Attorney General Jeff Sessions.

"The executive is empowered under the Constitution and by Congress to make national security judgments and to enforce our immigration policies in order to safeguard the American public," Sessions said. "Terrorism is clearly a danger for America and our people."

A senior Homeland Security official, speaking on background to reporters during a press call ahead of the remarks, insisted the new order, as with the last one, "is not a Muslim ban."

"This is a temporary suspension of entry of nationals from six countries that are either failed states, at this point, or are state sponsors of terror that we don’t have the ability to make safe, adequate, screening and vetting determinations for nationals under current procedures because of those weaknesses," the official said.

The executive order cites federal terrorism investigations of about 300 people who entered the country as refugees. However, senior administration officials declined to state whether those people under investigation came from any of the named countries. An internal three-page draft memo from Homeland Security obtained by the Associated Press and made public on Feb. 24 concluded that citizenship is "likely an unreliable indicator of terrorist threat in the United States."

Of the 82 people the government concluded were inspired by foreign terrorist groups to carryout attacks in the U.S., more than half were U.S. citizens, and the others hailed from more than two dozen countries. No citizen of any of the named countries has executed a terrorist attack in the U.S., and the countries together accounted for just a fraction of the visas granted in fiscal 2015, the memo said.

The DHS official on Monday's call with reporters dismissed the memo's findings, stating the document was "not completely, thoroughly vetted, cross-reported whatsoever."

In a ruling later unanimously upheld by a three-judge federal appellate panel, U.S. District Judge James Robart in Seattle issued an injunction in early February halting the travel restrictions because "there's no support" for the administration's assertion that “we have to protect the U.S. from individuals" from the nations named in the order.

The appeals court, in upholding the injunction, also cited the executive order's "immediate and widespread" impact and that the government had "pointed to no evidence" that an immigrant from any of the named countries had successfully launched an attack in the U.S.

The Trump administration has declined to appeal the injunction because it is issuing a new executive order. The new order, details of which were widely leaked ahead of Monday's announcement, has generally been seen as an attempt to address the courts' concerns and defend against legal challenges that are all but certain to be filed.

"We do not think they will have any merit moving forward, as we felt that the previous cases were also misguided and the judicial decisions were misguided based on a fully lawful E.O.," a senior Justice Department official, referring to the legal challenges to the executive order, said on Monday's call with reporters. The president is well within his independent and constitutional authority."

Trump and his administration had previously insisted that the travel restrictions were urgently needed.

"If we waited five days, 10 days, six months to begin establishing the first series of controls, we would be leaving the homeland unnecessarily vulnerable," senior policy adviser Stephen Miller said amid the confusion in the days after the original order was issued.

Homeland Security Secretary John Kelly told Congress on Feb. 7, however, that, "in retrospect," the previous order's rollout should have been delayed.

The release of the new order has been held up multiple times, and the topic has since received comparatively little public attention from Trump or other White House officials, causing some civil rights groups to contend that restrictions may not be as time-sensitive or crucial as the administration had claimed.

The new order was further delayed after the White House reportedly postponed announcing the new restrictions after positive reactions to the president's address to a joint session of Congress last week.

"The holdup flies in the face of the mythology as to why they needed to rush the bill in the first place," Doris Meissner, was head of the Immigration and Naturalization Service under President Bill Clinton, told the Associated Press. "It was a contrived argument and a reflection of inexperience and a rush to fulfill a campaign promise."

Nonetheless, senior administration officials maintained that by issuing a new order, rather than continuing to defend the original in court, Trump was effectively demonstrating how urgently the travel restrictions are needed.