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 controlling their own "plazas" for drug trafficking. Governmental authority was highly centralized under PRI (Partido Revolucionario Institucional, Institutional Revolutionary Party) rule and by bribing high officials, the drug smugglers could control their businesses without getting interrupted by the authorities. When single-party rule started to give way to local opposition 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.
Los Zetas was formed as the armed wing of the Gulf Cartel in the 1990s. Founded by deserters from the Mexican military's Special Forces Airmobile Group (GAFES, Grupo Aeromóvil de Fuerzas Especiales), the group has been referred to as the most formidable death squad to have worked for organized crime in Mexican history. As an answer to the creation of Los Zetas, the Sinaloa Cartel formed two armed wings of their own, Los Pelones and Los Negros. Fighting between Los Zetas and Los Negros is first registered in UCDP data in 2004. However, as Los Zetas was controlled by the Gulf Cartel these battles are included in the Gulf Cartel - Sinaloa Cartel conflict. Los Zetas officially split from the Gulf Cartel in early 2010 and is now battling the Sinaloa Cartel as an independent group. Fighting between Los Zetas and the gangs controlled by the Sinaloa Cartel are therefore since 2010 registered as a new dyad.
In 2011 it became clear that the numerous cartels and gangs active in Mexico had united in two alliances with the Gulf Cartel, the Sinaloa Cartel, Jalisco Cartel New Generation, Los Caballeros Templarios and La Barredora, on one side and Los Zetas, the Juarez Cartel, the Milenio Cartel, La Familia and the South Pacific Cartel, on the other.
Both Los Zetas and the Sinaloa Cartel use advanced weaponry such as grenade launchers, as well as assault weapons, to battle each other. Torture, decapitations, and mutilations of the victims' bodies are common. Some of the fighting between the cartels also takes place inside jails, for example in June 2010 when 29 people were killed in a prison in Sinaloa State.
In 2014 the violence between the two cartels increased in the area along the border to the US in Sonora state. However, looking at the total number of fatalities during the year it remained at a comparatively low level.
The non-state conflict between Los Zetas and the Sinaloa Cartel is first included in UCDP data in 2010. In June of that year, a clash in a state prison resulted in at least 29 battle-related deaths.
