Foreigners living in the United States who want a green card will have to leave the country and apply from their home nation, US Citizenship and Immigration Services (USCIS) announced on Friday, ending a half-century-old “adjustment of status” pathway that allowed applicants to complete the entire process inside the US.

The change applies to “nonimmigrants” — students on F-1 visas, H-1B and other work-visa holders, tourist-visa holders, refugees and political asylum seekers — and includes individuals married to US citizens. USCIS officers may grant exemptions only in “extraordinary circumstances”, the agency said.

“Nonimmigrants, like students, temporary workers, or people on tourist visas, come to the U.S. for a short time and for a specific purpose. Our system is designed for them to leave when their visit is over. Their visit should not function as the first step in the Green Card process,” the agency said in a statement carried by the Associated Press.

The shift will affect a large pool of applicants. Doug Rand, a former senior USCIS adviser during the Biden administration, told AP that about 600,000 people already in the US apply for green cards each year. “The goal of this policy is very explicit. Senior officials in this administration have said over and over that they want fewer people to get permanent residency because permanent residency is a path to citizenship and they want to block that path for as many people as possible,” he said.

Immigration attorneys said US consular wait times in some countries already exceed a year, raising the prospect of long separations for affected families. USCIS did not specify when the change takes effect or how it will be applied to applications already in process.

The policy is the latest in a series of measures by the Trump administration tightening legal immigration channels and has direct implications for the large Sri Lankan diaspora in the United States, including students, IT professionals on H-1B visas and family-reunification applicants.