MEXICO CITY — U.S. officials arrested a former Mexican secretary of defense on drug charges on Thursday, authorities said, a stunning development for a nation that honors its armed forces and has relied on them to fight narcotics traffickers.

The detention of retired Gen. Salvador Cienfuegos in Los Angeles was announced in a late-night tweet by Mexican Foreign Minister Marcelo Ebrard. The minister said he expected to be informed by Mexican consular officials of the charges in coming hours. A Mexican government official confirmed the arrest was requested by the U.S. Drug Enforcement Administration. He spoke on the condition of anonymity to describe information that was not yet public.

Cienfuegos, 72, was secretary of defense from 2012 to 2018 under then-President Enrique Peña Nieto.

Mexico’s military holds the lead role in fighting organized crime and has worked closely with U.S. anti-drug agencies. The Mexican armed forces have killed or arrested numerous top narcotics traffickers in recent years. But violence has grown and crime groups have penetrated towns and cities around Mexico, diversifying into an array of activities including kidnapping and extortion.

The Mexican police have been riddled with corruption for years — but U.S. officials had deemed the military more trustworthy. Still, Falko Ernst, the senior Mexico analyst for the International Crisis Group, said that military officers posted in some parts of the country were known to cut deals with trafficking groups.

“This myth of the cleanliness and incorruptibility of the armed forces has always been not really paired with reality,” he said.

The arrest comes as the Trump administration has been pressing Mexico to take tougher steps against trafficking organizations. The country is the source of almost all the heroin and methamphetamines arriving in the United States, and a major transit route for cocaine and fentanyl. In September, Trump said in an annual drug finding that Mexico “must clearly demonstrate its commitment to dismantling the cartels” and work harder to seize chemicals used in the production of fentanyl.

Cienfuegos was arrested at Los Angeles International Airport with his family. While charges were not announced, the Associated Press quoted an unidentified source as saying the arrest warrant listed drug trafficking and money laundering allegations.

Cienfuegos is the highest-ranking Mexican official to be detained in the United States since the arrest in December of Genaro García Luna, on allegations of taking millions of dollars in bribes from the Sinaloa cartel. García Luna, who served as minister of public security from 2006 to 2012, is expected to go on trial in New York in coming months. He has pleaded not guilty.

President Andrés Manuel López Obrador has criticized the “war on drugs” launched by his predecessors, using García Luna’s arrest to argue the strategy was a sham. The latest arrest may further erode popular support for the kind of offensives backed by the U.S. government.

López Obrador has continued cooperation with Washington on anti-narcotics, but he called for a greater focus on social spending to lure young people from joining crime gangs.

He has relied heavily on the military for a range of duties, from combating organized crime to building a new airport outside Mexico City.