WASHINGTON — The Trump administration on Thursday moved aggressively to fulfill one of the president’s most contentious campaign promises, banning entry into the United States by refugees from around the world and prohibiting most visitors from six predominantly Muslim countries.
Freed by the Supreme Court to partially revive President Trump’s travel ban, administration officials said the American border would be shut to those groups unless specific individuals can prove they have close family members living in the United States, or are coming to attend a university or accept a job offer.
Officials said those exceptions would be defined narrowly. In a lengthy cable sent to embassies and consulates around the world, officials said that extended family connections would not be sufficient to evade the president’s ban on entry. Parents, including in-laws, are considered “close family,” but grandparents are not, for instance. Stepsiblings and half-siblings will be allowed, but not nieces or nephews.
Critics immediately denounced the administration, accusing the White House of violating the Supreme Court’s directive to exempt anyone with a “bona fide” family connection to the United States. Civil rights groups vowed to challenge what they said was a renewed attempt by Mr. Trump to keep Muslims out of the country.
“It remains clear that President Trump’s purpose is to disparage and condemn Muslims,” said Omar Jadwat, director of the A.C.L.U.’s Immigrants’ Rights Project, adding that the government’s new ban on entry “does not comport with the Supreme Court’s order, is arbitrary, and is not tied to any legitimate government purpose.”
One week after taking office, Mr. Trump shut down travel from seven mostly Muslim countries, including Iraq, and blocked entry by all refugees, saying that a “pause” was necessary to evaluate the vetting of visitors from places that the government deemed dangerous.
Critics assailed that first order as a veiled attempt to make good on Mr. Trump’s campaign promise to impose a “Muslim ban.” After courts blocked it, the president issued a modified order directed at six countries, not including Iraq. That order was blocked as well, with federal appeals courts ruling that it discriminated based on religion, in violation of the First Amendment, and exceeded the president’s statutory authority.
The decision Thursday by the administration to revive and aggressively enforce another version of the president’s travel ban is certain to keep the intense debate about America’s borders going into the Supreme Court’s fall term, when the justices are scheduled to decide the legal fate of Mr. Trump’s efforts to restrict entry by particular groups.
Officials said they were determined to “meet the intent of the presidential directive” within the boundaries set by the Supreme Court, which issued an interim opinion when it agreed to consider the issue in its next term. Administration officials said their definition of a “family connection” was based on existing immigration law and directions from the court.
Hours before the new guidelines went into effect Thursday evening, officials predicted little of the chaos that engulfed airports in January, when the president issued his original travel ban. This time, officials said, people already booked to travel to the United States would be allowed to enter. And they made it clear that legal permanent residents were not affected by the ban.
But the administration’s newest move could prompt another wave of litigation as advocates for those trying to enter the United States ask courts to halt enforcement of the ban. Already, lawyers in Washington have filed a lawsuit asking the court to allow the entry of refugees with no “credible claim of a bona fide relationship with a person or entity in the United States.”
Other lawyers representing people who have been blocked from visiting the United States described the government’s actions as meanspirited and said they made distinctions about family relations that did not make practical sense.
“Allowing a U.S. citizen to bring their Syrian mother-in-law but not their Syrian brother-in-law doesn’t make us any safer, and doesn’t even really make any sense,” said Gadeir Abbas, a staff lawyer on the Council on American-Islamic Relations.
Mr. Trump has said that his travel ban does not directly target Muslims, although the six countries on the list that the president has deemed as dangerous — Iran, Libya, Somalia, Sudan, Syria and Yemen — are majority Muslim.
Javad Zarif, Iran’s foreign minister, condemned the administration’s move in a tweet, writing: “U.S. now bans Iranian grandmothers from seeing their grandchildren, in a truly shameful exhibition of blind hostility to all Iranians.”
For refugees fleeing civil wars and violence around the world, the administration’s action on Thursday means that a 120-day ban on entry from all countries will likely bar many of them from finding safety in the United States.
As of Wednesday night, 49,009 refugees had been allowed into the United States so far this fiscal year, which ends Oct. 1. Officials predicted that the new 50,000 cap would be reached by July 6, so refugees who are planning to travel after that date will not automatically be allowed into the country. Travel arrangements for refugees beyond July 6 will not be allowed until an assessment is made by the State Department, officials said.
Even after the 50,000 limit is reached, however, refugees with family ties that meet the new guidelines will be allowed into the United States, officials said.
“The U.S. government is once again unfairly changing the rules on refugees who, after fleeing for their lives, are now struggling to eat and to stay alive while they try to follow those rules,” said Mark Hetfield, president and chief executive of HIAS, a refugee and resettlement agency.
Lawyers for refugees said they interpreted the Supreme Court’s interim opinion as saying that refugees who have a longstanding connection to one of the refugee placement agencies would qualify to enter the United States.
But administration officials said the opposite on Thursday, telling reporters that the yearslong process that refugees undergo to be vetted and connected with communities in the United States did not, by itself, constitute a “bona fide relationship” with an institution in the United States.
Refugee agencies argued in a letter sent Wednesday to Secretary of State Rex W. Tillerson that their clients should pass muster.
“The order stated that a bona fide relationship with an entity should be ‘formal, documented, and formed in the ordinary course, rather than for the purpose of evading E. O.-2,’” Hans van de Weerd, chairman of the Refugee Council USA, the coordinating body for agencies that handle resettlement, wrote in the letter, referring to the president’s executive order. He added that refugee agencies only accept applicants who have already proven that “he or she has ties to the United States.”
Advocates for refugees and others also complained on Thursday that the administration had done little to show how their travel ban would protect American citizens and others living in the United States.
No Americans have been killed by terrorist attacks on United States soil undertaken by anyone from the six targeted countries since at least 1975, according to a Cato Institute study, and at a midday news conference top officials from the departments of State, Homeland Security and Justice would not answer how the president’s executive order would make the country safer.
In a briefing later in the afternoon, Heather Nauert, the State Department’s spokeswoman, said those officials were career employees charged with carrying out the order, not defending its politics. When asked to defend the order herself, Ms. Nauert, a political appointee, was halting in her response.
“With some of these countries, we would take issue certainly with the government of Iran, and some of the nations there can be concerns,” Ms. Nauert said. “And the American public could have legitimate concerns about their safety when we open our doors. And we want to open our doors to people who are willing to go through proper screening measures and who want to be here and want to be productive members of our society.”