The United States sent a group of migrants back to China on the first large deportation flight there since 2018, and said on Tuesday that it was working with Chinese authorities to arrange additional flights.

The deportation, on a charter flight, took place over the weekend in coordination with Chinese authorities, the Department of Homeland Security said. The department did not specify how many migrants were on the plane, but The Associated Press and The Wall Street Journal reported that 116 were deported.

U.S. and Chinese authorities were working together on additional removal flights, the statement said.

The announcement comes during an intense debate about immigration and border policy in the lead-up to the U.S. presidential election in November. Since last year, a growing number of Chinese migrants has made the journey into the U.S. through its southern border, hoping to escape bleak economic prospects and political oppression.

Many follow a route made popular on social media that takes them through the treacherous Darién Gap on the border of Panama and Columbia, the only land route north from South America as migrants head to the United States. Once they arrive at the southern border, they surrender to U.S. border officers and apply for asylum, citing a credible fear if they are sent back to China.

In the 2023 fiscal year, more than 24,000 Chinese migrants were temporarily detained on the U.S. southern border, according to U.S. Customs and Border Protection — more than in the preceding 10 years combined.

Last year, Chinese migrants became the fourth-largest group crossing into the U.S. that way, exceeded only by Venezuelans, Ecuadoreans and Haitians, according to Panama immigration authorities.

The Chinese Embassy in Washington did not immediately respond to requests for comment.