The Trump White House issued a proclamation on Friday that bans migrants caught entering the US unlawfully from seeking asylum.

The ban’s stated purpose is to funnel immigrants from Mexico and Central America to ports of entry along the border, where they will be allowed to apply for asylum “in an orderly and controlled manner instead of unlawfully.”

The ban is set to last for 90 days, or until such time as the US strikes a “safe third country” deal with the Mexican government.

The opening paragraph of the statement makes reference to the caravan of Central American migrants currently traveling through Mexico. It states that this group “appear[s] to have no lawful basis for admission into our country” and “intend to enter the United States unlawfully or without proper documentation and to seek asylum.”

Trump’s statement expresses concerns about potential abuse of the US asylum system by migrants, citing an increase in asylum claims by migrants caught crossing into the US illegally. It states that such practices “overwhelm” the asylum system and make it take longer to process “legitimate” claims.

Omar Jadwat, the director of the American Civil Liberties Union’s Immigrant Rights Project, stated that “The law is clear: People can apply for asylum whether or not they’re at a port of entry, and regardless of their immigration status” and that “The president doesn’t get to ignore that law, even if he dislikes it.”

The Central American migrant caravan has been adopted as a central issue by the president as well as many Republican candidates seeking office in the 2018 US midterm elections. The proclamation works in tandem with Thursday’s regulation that initially established the changes to asylum rules.