The United States government has announced a new immigration rule requiring many foreigners currently in the country on temporary visas to leave the US and apply for green cards from their home countries.

The policy, announced Friday by the US Citizenship and Immigration Services (USCIS), marks the latest effort by the Trump administration to tighten immigration procedures and limit pathways to permanent residency.

In a statement, USCIS spokesman Zach Kahler said that, “From now on, an alien who is in the US temporarily and wants a green card must return to their home country to apply, except in extraordinary circumstances.”

Kahler explained that the rule applies to nonimmigrants such as international students, temporary workers, and tourists who entered the US for short-term purposes.

“Nonimmigrants, like students, temporary workers, or people on tourist visas, come to the US for a short time and for a specific purpose,” he said. “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.”

According to USCIS, the new measure is intended to discourage visa overstays and reduce the number of people remaining in the country illegally after their residency applications are denied.

The administration has not yet clarified which visa categories or applicants will be most affected by the rule, raising uncertainty among immigrants currently seeking permanent residency in the United States.