US tightened restrictions on tourists arriving from the West African countries gripped by an Ebola outbreak, funneling them into five airports with extra health checks.
The Department of Homeland Security ordered passengers whose journeys begin in Guinea, Liberia or Sierra Leone to fly to New York's JFK or Newark airports, Washington Dulles, Atlanta or Chicago.
The new measures go into effect Wednesday.
There are no direct scheduled flights to the United States from the three countries at the heart of the Ebola epidemic, but travelers from the region can transfer through African and European hubs.
One Liberian with Ebola arrived in Dallas, Texas and infected at least two US health workers before dying earlier this month, piling pressure on President Barack Obama's government to impose a flight ban.
Health authorities have set up additional screening at five ports of entry, airports which they say normally handle 94 percent of the travelers arriving from the three worst-hit countries.
But Tuesday's order would prevent travelers from Guinea, Liberia or Sierra Leone from transferring to flights to other US airports where they would not necessarily have to pass additional screening.
"If not already handled by the airlines, the few impacted travelers should contact the airlines for rebooking, as needed," Homeland Security Secretary Jeh Johnson said.
"We currently have in place measures to identify and screen anyone at all land, sea and air ports of entry into the United States who we have reason to believe has been present in Liberia, Sierra Leone or Guinea in the preceding 21 days."
The virus has killed more than 4,500 people in West Africa this year, and stoked fears that it could spread beyond the three worst-hit countries and become a global threat.
But small outbreaks in Senegal and Nigeria have been halted and, with no new confirmed infections in the United States for six days, authorities are hopeful they have contained the danger here.
- Lawmakers urge stricter measures -
Congressman Michael McCaul, a Texas Republican who chairs the House Homeland Security Committee, hailed the DHS move as "a common sense proposal."
However, he joined many US lawmakers, including some Democrats, in urging even stricter measures to keep out travelers from West Africa.
"I continue to call on the administration to suspend all visas from Liberia, Sierra Leone and Guinea," he said in a statement.
Sixteen lawmakers who have worked as doctors or nurses wrote Obama on Tuesday calling for tighter restrictions, including a 21-day quarantine before entering the US for Americans exposed to Ebola.
"Containment is the key to stopping the spread of this highly contagious and deadly disease, and we strongly urge your administration to consider implementing a temporary travel ban for individuals who are citizens of, or travelled to, affected countries in West Africa," the lawmakers wrote.
Republican Senator Marco Rubio said he will introduce legislation next month, when Congress resumes in Washington after the current recess, that would ban the issuance of new visas from afflicted countries until the outbreak is contained.