Donald Trump's travel ban has been expanded to eight countries, with citizens of North Korea, Venezuela and Chad joining the list of those restricted.
But one country, Sudan, will no longer be subject to strict visa controls.
The north-east African nation was one of the six Muslim-majority countries - also including Iran, Libya, Syria, Yemen and Somalia - whose citizens were barred from entering the US under the previous travel ban, which expired on Sunday.
The White House has given no official statement on Sudan's removal from the revamped restrictions.
Administration sources attributed the decision to the country's co-operation with the US government on national security and information-sharing, the Washington Post reported.
But some have suggested the move was politically motivated.
"Sudan getting dropped from the travel ban comes as the UAE has been lobbying hard for them in DC in exchange for mercenary support in Yemen," tweeted Ryan Grim, Washington bureau chief at The Intercept.
Sudan has supplied thousands of troops to support the Saudi-led coalition, also including the United Arab Emirates and other Middle Eastern countries, to help fight Houthi rebels in Yemen's civil war. The US has also provided "logistical support" to the coalition.
Sudan remains one of three countries, alongside Iran and Syria, listed by the US government as a state which sponsors terrorism.
The designation, which has been in place since 1993, means the country is subject to sanctions including restrictions including a ban on arms sales by American companies and tighter export controls.
In July, the US State Department delayed a decision on ending certain sanctions and called on the Sudanese government to maintain "positive actions" including ceasefires in conflict-torn areas, improved humanitarian access, and "co-operation with the United States on addressing regional conflicts and the threat of terrorism".
Mr Trump has said the updated travel ban is needed to screen out terror threats.
In a statement on Sunday night, the White House described the new restrictions as a “critical step toward establishing an immigration system that protects Americans' safety and security in an era of dangerous terrorism and transnational crime.”
"We cannot afford to continue the failed policies of the past, which present an unacceptable danger to our country,” President Trump said in the statement. “My highest obligation is to ensure the safety and security of the American people, and in issuing this new travel order, I am fulfilling that sacred obligation.”
The addition of North Korea and Venezuela broadens the restrictions from original, mostly Muslim-majority list, which sparked international outrage and was quickly blocked by federal courts as unconstitutional discrimination or a violation of immigration law.
In June, the US Supreme Court allowed a limited version of the ban to go ahead while justices examine its legality.
Experts said the new restrictions, set to come into effect on October 18, could be less vulnerable to legal attack because it is the result of a month-long analysis of foreign vetting procedures by US officials and may be less easily tied to Mr Trump's campaign-trail attacks on Muslims.
Ahead of the election the Republican promised a "total and complete shutdown on Muslims entering the United States".
"The greater the sense that the policy reflects a considered, expert judgment, the less the temptation [by courts] to second-guess the executive," said Saikrishna Prakash, a professor at the University of Virginia School of Law. "It looks less like a matter of prejudice or a desire to fulfill a campaign promise."
The new ban indefinitely restricts travel to the US from Iran, Libya, Syria, Yemen, Somalia, Chad and North Korea. Only certain government officials from Venezuela will be barred.
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