Guatemala has signed a comprehensive migration reform deal which allows U.S. border officials to legally block asylum claims by migrants who pass through that country, President Donald Trump said Friday.

The migration deal “is going to be terrific for them and terrific for the United States. This landmark agreement will put the coyotes and the smugglers out of business… [and] will usher in a new era and investment and growth for Guatemala,” said Trump.

Pro-migrant groups denounced the deal, which reportedly says the U.S. need not consider asylum claims by migrants who travel through Guatemala. The impact could be huge, because most migrants from Central America, South America, Africa,and Asia travel through Guatemala, as it occupies the full width of the land bridge between Mexico and South America.

Kevin McAleenan, the acting secretary of the Department of Homeland Security, described the deal in an Oval Office press conference. Migrants “can make a protection [asylum] claim, if they would like, in Guatemala, so if they arrive in the U.S., not having availed themselves of that authority, they will be returned to Guatemala.”

The deal does not bar U.S. asylum claims by people from Guatemala, but Trump’s migration deal with Mexico has largely stopped migrants from Guatemala.

The full details of the deal were not immediately released by the administration.

Pro-migration groups are denouncing the deal as illegitimate under U.S. and international laws that govern asylum and migration.

“I saw one report saying that the asylum office in Guatemala has just 12 employees,” said a tweet from Aaron Reichlin-Melnick, an advocate at the pro-migration Immigration Council. “Over the past few years, Guatemala has averaged 90 asylum applications per year. NINETY. The idea that Guatemala can offer a “full and fair” asylum system to those fleeing persecution is a farce.”

“Guatemala is not a safe country,” said a tweet from the Texas-based Refugee and Immigrant Center for Education and Legal Services. “250k+ people fled since Oct. Good background here on climate crisis leading to this [New Yorker article]… It has the highest rate of femicide (the killing of a woman or girl, in particular by a man & on account of her gender) in the world.”

Pro-migration groups also say Trump is unfairly using U.S. political and economic power — such as foreign aid — to force Guatemala to make the deal, which gives Trump a legal end-run around the U.S. establishment’s preference for a loose-borders, high-migration, low-wage economy.

The deal was expected in early July, but the Guatemalan government backed away this week amid protests by voters and statements against the deal by the nation’s top court.

Pro-migration groups also say the deal is illegitimate under Guatemalan law. “The Constitutional Court in Guatemala granted three injunctions preventing its government from entering into a deal only a few weeks ago,” said a statement from RAICES. “It’s unclear what authority this Guatemala gov representative has.”

Many pro-migration groups — including Democrats, U.S. employers, retail firms, and immigration lawyers — have opposed a migration deal with Guatemala.

“I guess the Guatemalan president said ‘screw the law’ too,” said a tweet from David Bier, an advocate at the business-funded pro-migration CATO Institute. “Even as the federal government fought to keep its asylum ban policy in place, it presented NO EVIDENCE to the court of the existence of an asylum system in Guatemala at all,” he added in another tweet.

Guatemala’s government is facing an election which may endorse or reject the deal.

The deal is a big win for Trump in the broader back-and-forth political struggle with the establishment of pro-migration politicians, judges, investors, and activists throughout the United States. In recent weeks, Trump has pocketed some gains — a shift in public opinion in Mexico and new U.S. repatriation policies, for example  — and has taken losses, such as a California judge’s decision to block Trump’s reforms of asylum procedures.