The leader of the notorious Sinaloa drug trafficking cartel in Mexico has been arrested along with the son of notorious kingpin El Chapo in Texas.
Ismael "El Mayo" Zambada and Joaquin Guzman Lopez, the son of his ex-partner Joaquin "El Chapo" Guzman, were arrested on Thursday in El Paso by US authorities.
Zambada is one of the most consequential traffickers in Mexico's history and co-founded the Sinaloa Cartel with El Chapo, who was extradited to the United States in 2017 and is serving a life sentence in a maximum security prison.
Both Zambada and Guzman Lopez face multiple charges in the US for funnelling huge quantities of drugs to American streets, including fentanyl, which has surged to become the leading cause of death for Americans between the ages of 18 and 45.
Zambada, who is believed to be in his 70s, and Guzman Lopez, who is in his 30s, were detained after landing in a private plane in the El Paso area, two US officials told Reuters.
Guzman Lopez is one of four sons of El Chapo - known as Los Chapitos, or Little Chapos - who inherited their father's faction of the Sinaloa Cartel.
His brother, Ovidio Guzman, was arrested last year and extradited to the United States.
In recent years, the Sinaloa Cartel has become the biggest target for US authorities, who have accused the crime syndicate of being the biggest supplier of fentanyl to the United States.
Zambada and Guzman Lopez face multiple charges in the US "for heading the Cartel’s criminal operations, including its deadly fentanyl manufacturing and trafficking networks," US Attorney General Merrick Garland said in a statement.
"Fentanyl is the deadliest drug threat our country has ever faced, and the Justice Department will not rest until every single cartel leader, member, and associate responsible for poisoning our communities is held accountable," he added.
One worker at the Santa Teresa airport, near El Paso, on Thursday afternoon told Reuters that he saw a Beechcraft King Air land on the runway, where federal agents were already waiting.
"Two individuals got off the plane and were calmly taken into custody," said the man, who declined to share his name out of concern for his safety.
"It seemed like a pretty calm, arranged thing," he added.
The US authorities had a $15 million reward for Zambada's capture, while Guzman Lopez had a $5 million bounty on his head.
The Sinaloa cartel traffics drugs to more than 50 countries around the globe and is one of the two most powerful organised crime groups in Mexico.
Zambada and El Chapo's sons belong to two different generations of traffickers, with differing styles.
Zambada is known for being an "old-school" narco, avoiding the limelight and operating in the shadows.
El Chapo's sons, by contrast, have a reputation for being flashy narcos who courted attention as they ascended the ranks of the cartel.
El Chapo's sons are also known to be more violent and hot-headed than Zambada, who had a reputation as a shrewd operator.
Zambada and El Chapo's sons have had a fractious relationship since their father was extradited in 2017, and the arrests of Zambada and Guzman Lopez may trigger instability or even violence in their heartlands in the northern state of Sinaloa.
Previous arrests of important cartel leaders have triggered violence as power vacuums open, leading to significant infighting within the organisations and between them and their rivals.
"This possibility certainly looms very large," said Vanda Felbab-Brown, a researcher at Washington's Brookings Institution who closely monitors Mexican security.
Their arrests were part of a joint operation by the Federal Bureau of Investigation (FBI) and Homeland Security Investigations (HSI) agencies, HSI said in a statement.
US authorities have over the past year launched fresh indictments against Zambada and Guzman's sons on new charges in the United States that focus on fentanyl smuggling, as well as the flow of precursor chemicals to the illicit labs operated by their crime syndicate.
Over decades, the cartel has set up sophisticated supply chains to move drugs across the globe and to source heavily regulated chemicals to their home base in Sinaloa.