From the introduction of the article, by John P. Sullivan and Samuel Logan, published in "The Counter Terrorist," a magazine produced by the organization Security Solutions International.
Los Zetas are arguably Mexico's most ruthless and tactically proficient criminal gang. Essentially enforcers turned multipurpose cartel, they are waging a brutal war against competing cartels and the Mexican state alike. The Zetas' current situation is one of flux. They are under immense pressure from both the state and criminal competitors. As a result, they are waging an increasingly brutal campaign to retain relevancy and expand their power base.
They could emerge from their current situation stronger by consolidating power and expanding their reach, or, the backlash to their campaign could force them off the table. Either way, Los Zetas have changed the game forever in Mexico.