Los Zetas, the enforcer of Mexico´s infamous Gulf Cartel, is reinforcing its ranks and stockpiling weapons in safe houses in the U.S

Los Zetas, the enforcer of Mexico´s infamous Gulf Cartel, is reinforcing its ranks and stockpiling weapons in safe houses in the U.S. in response to recent crackdowns in the U.S. and Mexico against drug traffickers, said the FBI San Antonio Field Office's Joint Assessment Bulletin. The bulletin was dated Oct. 17 and was sent to law enforcement officials in the Texas region. The bulletin said the cartel's regional leader, Jaime Gonzalez, has ordered the reinforcements to a tactical operational territory, or "plaza," in the area around the southern Texas towns of McAllen and Mission, about 235 miles south of San Antonio and less than five miles from the border with Mexico. "In direct response to recent United States law enforcement activities against Los Zetas members of the McAllen-Mission, Texas Plaza, Jaime Gonzalez, AKA 'HUMMER,' has ordered additional personnel to the Plaza to regain control and engage law enforcement officers if confronted," states the bulletin, which was produced by the FBI's McAllen Intelligence Center. "These replacements are believed to be armed with assault rifles, bullet proof vests, and grenades, and are occupying safe houses throughout the McAllen Texas area," the bulletin states. Richard Kolko, a spokesman for the FBI in Washington, confirmed the authenticity of the report. "The FBI, with our gang task force members are well aware of Los Zetas and their violent nature. A bulletin not intended for the media was provided to law enforcement throughout Texas to alert them of potential new tactics," he said. Los Zetas is thought to be composed of former members of Mexico´s special forces who deserted or retired to work for the Gulf Cartel, a Drug Enforcement Administration (DEA) official familiar with the group told The Times. The official, who spoke on the condition of anonymity because of ongoing operations in the area, said that Los Zetas is thought to have taken control of the Gulf Cartel's operations. Its home base in Nuevo Laredo, a Mexican border town about 160 miles southwest of San Antonio, has been brutalized by ongoing cartel wars and witnessed a surge of violence in recent years. Recent arrests by the FBI of several members associated with the McAllen-Mission plaza led to the information on the drug cartel's intentions and on Mr. Gonzalez. Mr. Gonzalez, who operates out of Reynosa, Mexico, about 10 miles south of McAllen and Mission, instructed his cells to "engage law enforcement with a full tactical response should law enforcement attempt to intervene in their operations" and also is "believed to have established loose relationships with street and prison gangs to facilitate their movement and operations within the United States," according to the bulletin. An FBI search warrant on a rural location in Mission resulted in the seizure of multiple weapons including assault rifles, tactical vests, and an assortment of paintball weapons, which the Zetas have used for "regular paint ball training for tactical raids and car stops," the bulletin states. According to the bulletin, the "main responsibility of these cells" stationed in the United States "is to seek out people owing the Cartel money for lost, stolen, seized drug loads or profits." Those people are forced to "either pay their debt or are kidnapped. In addition, the plaza cells are proactively seeking out and eliminating rival drug and alien smuggling groups," the bulletin states. Since the summer, drug wars have escalated along the more than 2,000-mile U.S. border with Mexico, with thousands killed. Los Zetas, continues to control the drug routes in the south Texas area, which includes access to Interstate 35 and Highways 59, 359 and 83. The interstates run from south Texas to as far north as Canada and provide the drug cartels access to major U.S. cities, where they distribute billions of dollars in narcotics annually. The FBI McAllen Resident Agency, a division of the bureau's San Antonio Field Office, recently received the information that the Zetas have segregated the Rio Grande Valley area into tactical operational territories, or plazas, and "currently have standing orders to confront U.S. law enforcement agencies to zealously protect their criminal interests," the bulletin states. Each territory or "plaza" has a designated leader to oversee all enforcement operations conducted on behalf of the cartel. Increased pressure by U.S. and Mexican law enforcement has pushed the cartels "into a defensive mode," the DEA official said. "These particular types of activities by the cartels show their increased strength and the serious threat they pose to the national security in the U.S.," the official said. "It's not getting better but worse along the border. Unfortunately, the drug wars we've seen in Mexico are now spilling significantly into the United States."