Over recent months, the level of violence along the U.S.-Mexican border has begun to rise substantially, with some of it spilling into the United States. Last week, the Mexican government began military operations on its side of the border against Mexican gangs engaged in smuggling drugs into the United States. The action apparently pushed some of the gang members north into the United States in a bid for sanctuary. Low-level violence is endemic to the border region. But while not without precedent, movement of organized, armed cadres into the United States on this scale goes beyond what has become accepted practice. The dynamics in the borderland are shifting and must be understood in a broader, geopolitical context.