SUMMARY

The outbreak of fighting between different drug-trafficking gangs in Mexico can be understood against the background of changes in the Mexican political landscape during the last decades. During the 1980s, there was a loose network of drug smugglers who controlled separate territories, known as "plazas", which they used primarily for drug trafficking. Governmental authority was highly centralized under PRI (Partido Revolucionario Institucional, Institutional Revolutionary Party) rule and by bribing high ranking officials the drug smugglers could conduct their operations largely uninterrupted by the authorities. When single-party rule started to give way to opposition parties in the late 1990s and early 2000s these networks and relationships were transformed, to the advantage of some actors but to the disadvantage of others. The drug cartels started to fight each other for control over territory and previous alliances fell apart.

Created in the middle of the 1990s by a group of deserters from the Mexican military's Special Forces Airmobile Group (GAFES, Grupo Aeromóvil de Fuerzas Especiales), Los Zetas was previously the armed wing of the Gulf Cartel and loyal to leader Osiel Cardenas. When Cardenas was ultimately arrested and in 2007 and extradited to the U.S., Los Zetas became more independent and eventually grew more powerful than the Gulf Cartel. In early 2010 Los Zetas officially split from the Gulf Cartel and started fighting their former allies for control over their territories.

Fighting between the Gulf Cartel and Los Zetas has been concentrated in Tamaulipas and Nuevo Leon states, but has also taken place in other areas along the Gulf coast. The Gulf Cartel used to be dominant along most parts of the coast but was pushed back by Los Zetas in 2010.

Both the Gulf Cartel and Los Zetas use advanced weaponry such as grenade launchers, high caliber weapons and assault rifles, to battle each other. Torture, decapitations and the mutilation of victims is common. Threatening messages to the groups' leaders are often found next to the victims' bodies.

The non-state conflict between the Gulf Cartel and Los Zetas is first included in UCDP data in 2010. By March of that year fighting between the two cartels had resulted in more than 50 battle-related deaths.