Mexican authorities have confirmed that Nemesio Oseguera Cervantes, widely known as “El Mencho,” has been killed in a major security operation, marking what officials describe as a significant development in the country’s fight against organised crime. Oseguera, the longtime leader of the Jalisco New Generation Cartel, was reportedly killed on Sunday during a raid in Tapalpa, a town in Jalisco state. Authorities have yet to disclose full details of how the operation was carried out. According to the New York Times, El Mencho had built a reputation as one of Mexico’s most dangerous and powerful drug traffickers. Over the past decade, the CJNG expanded rapidly under his leadership, developing a sprawling criminal enterprise involved in drug production, international trafficking, extortion and violent control of territory. The cartel became known for bold, coordinated attacks against security forces and for unleashing waves of violence across several Mexican states. Shortly after news of his death broke, unrest flared in at least five states. Residents reported that vehicles were set on fire and used to barricade highways — a tactic frequently employed by cartels to disrupt movement and signal retaliation. In Jalisco, officials suspended public transport services in certain areas and urged residents to remain indoors. Some disturbances were reported in Guadalajara, the state capital and one of Mexico’s largest cities. Security analysts warn that the killing of Nemesio Oseguera Cervantes could lead to further instability. Although his death represents a symbolic victory for the government, experts say it may spark violent power struggles within the CJNG, while rival criminal groups attempt to seize territory. Past high-profile takedowns of cartel leaders have often resulted in fragmentation and increased bloodshed rather than immediate peace. The development also carries international implications. U.S. President Donald Trump has repeatedly pressed Mexico to intensify its campaign against drug cartels, at times threatening unilateral military action if stronger measures were not taken. Mexico’s President Claudia Sheinbaum has rejected any suggestion of U.S. military intervention, describing such proposals as violations of Mexico’s sovereignty. Nevertheless, her administration has strengthened intelligence-sharing and security cooperation with Washington amid tensions over fentanyl trafficking and border security. The CJNG has been identified as a major supplier of synthetic drugs, including methamphetamine and fentanyl, to the United States, contributing to the ongoing opioid crisis. The U.S. government had previously offered a $15 million reward for Oseguera’s capture. As officials prepare to release more information about the operation, concerns remain that the aftermath of his death could trigger renewed violence in parts of the country.