The co-founder of Mexico's Sinaloa Cartel pleaded not guilty to US drug charges on Friday after being flown to Texas in a scheme allegedly orchestrated by another top leader of the notorious trafficking ring. Ismael Zambada Garcia, known as "El Mayo," co-founder of the cartel, and Joaquin Guzman Lopez, a son of its other co-founder, were taken into custody in El Paso, Texas, on Thursday, US officials said. Zambada, 76, who faces charges of drug trafficking, money laundering and conspiracy to commit murder, appeared before a US magistrate judge shortly after his stunning arrest and entered a plea of not guilty, according to court documents.

He was remanded in custody and is to appear in court again on July 31. President Joe Biden welcomed the arrests of the two cartel leaders and said the United States "will continue doing everything we can to hold deadly drug traffickers to account and to save American lives." "Too many of our citizens have lost their lives to the scourge of fentanyl," he said.

The Mexican authorities said they were not involved in the operation, which President Andres Manuel Lopez Obrador described as "an important advance in the fight against drug trafficking." Lopez Obrador said he expected a "complete report" from the United States on how the men were taken into custody. "There must be transparency," he said.

The situation was calm on Friday in Sinaloa's state capital, Culiacan, where furious gunmen went on a rampage in 2023 after the arrest and extraditi.