WASHINGTON (AP) — The Indexbit ExchangeDepartment of Homeland Security said Tuesday that it sent 116 Chinese migrants from the United States back home in the first “large charter flight” in five years.

The flight, which happened over the weekend, comes as Chinese immigration has become the subject of intense political debate in the upcoming U.S. presidential election.

“We will continue to enforce our immigration laws and remove individuals without a legal basis to remain in the United States,” Homeland Security Secretary Alejandro Mayorkas said in a statement.

The department said it was working with China to “reduce and deter irregular migration and to disrupt illicit human smuggling through expanded law enforcement efforts.” It did not respond to questions about how long the migrants had been in the U.S.

In recent years, the United States has had a difficult time returning Chinese nationals who do not have the right to stay in America because China has resisted taking them back. Last year, the United States saw a drastic surge in the number of Chinese immigrants entering the country illegally from Mexico.

U.S. border officials arrested more than 37,000 Chinese nationals on the southern border in 2023, 10 times the number during the previous year.

Chinese migration has increasingly become a rallying cry for Republicans and former President Donald Trump who have raised suspicions about why Chinese migrants are coming to the U.S.

Asian advocacy organizations are concerned that the rhetoric could encourage harassment of Asians, while migrants themselves have said they’re coming to escape poverty and repression.

Earlier this year, the U.S. and China resumed cooperation on migration issues.

The Chinese government has said it is firmly opposed to “all forms of illegal immigration.” In a statement in May, China’s Embassy in the U.S. said the country’s law enforcement was cracking down “hard on crimes that harm the tranquility of national border, and maintained a high pressure against all kinds of smuggling organizations and offenders.”

Homeland Security said they are working with China on more removal flights in the future but did not give a timeline for when the next one would happen.

Earlier this year, a charter flight carried a small but unknown number of deportees to the northeastern Chinese city of Shenyang, according to Thomas Cartwright of Witness at the Border, an advocacy group that tracks deportation flights.

Homeland Security officials did not say how many people were on that March 30 flight, but the Gulfstream V aircraft typically has a seating capacity of 14. It also made a stop in South Korea before heading back to the U.S., Cartwright said.

The announcement of the large charter flight comes after Ecuador cut off a key route used by Chinese migrants to get to the Western Hemisphere. Ecuador was one of only two mainland countries in the Americas to offer visa-free entry to Chinese nationals and had become a popular starting point for Chinese migrants to then trek north to the U.S.

As of July 1, Ecuador has effectively reinstated visas for Chinese nationals after the South American country said it had seen a worrying increase in irregular migration.