WASHINGTON (AP) — The United States on Tuesday sanctioned a son of Mexican drug lord Joaquin “El Chapo” Guzman, three members of the powerful Sinaloa cartel and two Mexican-based firms, alleging they trafficked fentanyl and other drugs into the US.

The sanctions came the day Mexican President Andrés Manuel López Obrador talked with President Joe Biden by phone about immigration and the fentanyl crisis.

A White House readout of the call said the two presidents recognized their nations’ recent efforts to counter fentanyl and arms trafficking “by dismantling criminal networks.”

The Treasury Department designated El Chapo’s son Joaquin Guzman Lopez and others for financial sanctions, including a freeze on American-owned assets and bank accounts and a ban on Americans doing business with them. A Culiacan, Mexico, chemical and lab equipment company and a real estate business also were targeted for sanctions.

The latest penalties by the Treasury’s Office of Foreign Assets Control follow a set of April fentanyl trafficking charges brought against three other Guzman sons, Ovidio Guzmán López, Jesús Alfredo Guzmán Salazar and Iván Archivaldo Guzmán Sálazar, known as the Chapitos, or Little Chapos, and two dozen members of the Sinaloa cartel.

El Chapo was extradited in 2017 to the US, where he was convicted of a massive drug conspiracy that spread murder and mayhem for more than two decades. He was sentenced in 2019 to life in a US prison.

Fentanyl is the deadliest drug in the US today. The Centers for Disease Control and Prevention estimates that 71,000 people died in the US from overdosing on synthetic opioids such as fentanyl in 2021, up from about 58,000 the year before.

López Obrador has denied that drug cartels make fentanyl in Mexico, although he has acknowledged that precursor chemicals and finished fentanyl are smuggled into Mexico from China, a claim China has denied.

Mexico and China are the primary sources for fentanyl and fentanyl-related substances trafficked directly into the US, according to the Drug Enforcement Administration, which is tasked with combating illicit drug trafficking.

Growing tensions between the US and China on multiple fronts have made efforts to stop the importation of fentanyl more difficult, according to a Congressional Research Service report.

Most of the fentanyl trafficked in the United States comes from the Sinaloa cartel, the DEA says.

The Treasury’s undersecretary for terrorism and financial intelligence, Brian Nelson, said that the department “in close coordination with the Government of Mexico and US law enforcement, will continue to leverage our authorities to isolate and disrupt Los Chapitos and the Sinaloa Cartel’s operations at every juncture.”

Guzman Lopez was not in custody Tuesday, and it was unclear if he had a lawyer who could speak on his behalf about the sanctions. A lawyer for El Chapo didn’t immediately return a message seeking comment.