Drug seizures have increased at ports up and down Mexico's West Coast, as enforcement agencies fight for control of shipping hubs under the sway of violent cartels.

On July 11, P&I Services Mexico — an company that handles insurance claims for various maritime entities — put out an alert, warning their clients of "a sudden increase in narcotics incidents" at ports across the western coast of Mexico. P&I Services noted that drugs have mostly been found in shipping containers or vessel sea chests (the grated openings on hulls that allow ships to take on small amounts of sea water). 

This comes months after the U.S. Drug Enforcement Administration (DEA) released a lengthy report detailing how Mexico's Sinaloa and Jalisco New Generation (CJNG) Cartels "are at the heart" of North America's drug crisis, sending a flood of synthetic drugs such as fentanyl and methamphetamine over the border. At the center of the cartels' power and influence is a complex distribution network rooted in Mexico's busiest ports. 

"Infrastructure-wise, it's critical for them to control a port," says Brian Townsend, who served with the DEA for 23 years as a supervisory special agent, among a variety of other roles. 

Townsend describes how cartels like CJNG and Sinaloa will rely on Chinese chemical and pill press companies to smuggle precursor chemicals in shipments to Mexico, which are used to manufacture drugs that are then smuggled into the U.S. and South America. With cartels controlling key ports situated in the heart of their respective territories, they're able to maintain a fully-functioning supply chain that makes up the backbone of their operations. 

For the Sinaloa Cartel, the Port of Mazatlan is essentially "their backyard," Townsend says, where legitimate carriers at the West Coast gateway have to constantly be on guard to ensure their own shipments aren't being co-opted. Sinaloa also has access to the CJNG-controlled Port of Manzanillo, one of Mexico's largest shipping hubs by volume. Carriers then have to deal with higher costs — and oftentimes delays — brought on by increased security measures, more thorough cargo inspections, and having to comply with enforcement agencies when a shipment gets seized. 

"It's just the cost of doing business," Townsend says. "They understand that this is a country that has a problem with precursor chemicals and other criminal activity coming through the ports throughout Mexico — they have to just figure out how to navigate those challenges."

As for the recent increase in drug seizures at Mexico's ports, Townsend points to a "strategic focus" on Sinaloa and CJNG by local agencies and the DEA, particularly as Mexico has sought to curb its own overdose crisis. That's part of a larger "cat and mouse game" where authorities know they can't fully wrest control of the country's ports away from cartels, and instead focus on carving out enough of a law enforcement presence at ports to keep trade flowing and allow legitimate businesses to continue operating at the crucial shipping hubs. Without that, Townsend says that the cartels would cause enough chaos to make it difficult for businesses to use those ports at all. 

Townsend says that the DEA is meanwhile likely looking to target "high-level traffickers" and leaders within each cartel. That seems confirmed by the arrest of Sinaloa cartel head Ismael Zambada in El Paso, Texas on July 25. According to CNN, attorneys for Zambada claim that he was kidnapped and forced onto a plane to the U.S. by the son of infamous Sinaloa co-founder Joaquin "El Chapo" Guzman. Zambada has led the Sinaloa cartel for decades, and was the last remaining fugitive on Mexico's 2009 list of 37 most-wanted drug lords.