The Biden administration announced Friday that it is increasing cooperation with Mexico to combat fentanyl trafficking entering the northern US, while also cracking down on arms trafficking entering southern Mexico.

NBC News was the first to report that the two countries were negotiating such an agreement.

On Friday, the Justice Department also unsealed charges in three federal courts against the Sinaloa cartel for fentanyl trafficking, including charges against four sons of jailed drug kingpin Joaquín «El Chapo» Guzmán, and the Treasury Department announced sanctions against two Chinese companies and five people. in China and Guatemala for their alleged role in trade.

At times, Mexico has resisted cooperating with the US on the issue of the fight against fentanyl. Most of the illicit supply of the powerful synthetic opioid entering the US is made in Mexico from raw materials shipped from China.

Mexican President Andrés Manuel López Obrador said in a speech in March that fentanyl is a US problem and that no drug is produced in his country.

“We don’t produce fentanyl here and we don’t have fentanyl consumption,” López Obrador said, suggesting that the US instead address its “social breakdown” problem.

A delegation of Mexican officials met with the Biden administration on Thursday, the White House said, and agreed to implement a strategy to combat fentanyl first agreed upon by Biden and López Obrador in January.

“This special task force will improve coordination among Mexican federal government entities to support the investigation and arrest of individuals involved in the production and trafficking of fentanyl. The United States and Mexico pledged to continue working together to dismantle the fentanyl supply chain and the Sinaloa Cartel and the Jalisco Nueva Generación Cartel on both sides of the border,» the White House said in a statement, referring to the cartels. Mexican drug dealers heavily involved in the production and manufacture of fentanyl.

A sticking point for the Mexicans in negotiations with the Americans over fentanyl, as NBC News previously reported, was the large number of US-made weapons ending up in Mexico, contributing to violence in the country. As part of the negotiations, the Justice Department agreed to do more to track the flow of weapons from the US to Mexico.

“The Department of Justice (DOJ) and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) are deploying new Bipartisan Safer Communities Act authorities to target southbound flows of firearms and working with their Mexican counterparts to increase firearms tracing to identify and asphyxiate the source of firearms flowing into Mexico,» the White House said in its statement.

Several sources familiar with the negotiations have stressed that the further commitment to cooperation is not itself a formal «agreement» between the countries and there will still be room for improvement and the need to see results from both sides.

On Friday, the Justice Department announced federal charges in New York, Illinois, and Washington, D.C. against several Sinaloa Cartel leaders and alleged associates: more than two dozen defendants in all, including the four «Chapitos,» or sons of «El Chapo» Guzman.

Attorney General Merrick Garland said the department had taken «significant enforcement action against the world’s largest, most violent and prolific fentanyl trafficking operation, led by the Sinaloa Cartel and powered by Chinese precursor pharmaceutical and chemical companies.»

Ken Dilanian contributed.