An MS-13 gang member claims to have received paramilitary training from the Sinaloa Cartel to fight against Los Zetas in Mexico, according to an interview conducted by Univision Noticias. 

In 2016, after Joaquin El Chapo Guzman’s capture, the Sinaloa Cartel contacted MS-13 gang members in California for assistance against the violent Zetas. Around 25 gang members volunteered and underwent training in a paramilitary camp in Sinaloa led by a former U.S. Navy member. The training covered various skills, including combat techniques, weapon handling, and swimming. 

After training, the gang members were deployed to northeastern Mexico for a six-month “war” against Los Zetas. 

According to the Univision report, the relationship between MS-13 and the cartels goes back to the 1990s when the Mara Salvatrucha aligned with the Mexican Mafia in California.