The U.S. State Department is warning travelers about "brutal" drug-related violence sweeping many regions of Mexico, the Fort Worth Star-Telegram reported Sept. 19.

The warning singled out Nuevo Laredo, across the border from Laredo, Texas, as one of the most dangerous places for American travelers to Mexico; the city has become a battleground in a turf war between the Gulf and Sinaloa drug cartels.

"U.S. citizens residing and traveling in Mexico should exercise extreme caution when in unfamiliar areas and be aware of their surroundings at all times," the warning noted. "Public sources suggest that narcotics-related violence has claimed 1,500 lives in Mexico this year." Execution-style killings and kidnappings have targeted U.S. citizens as well as Mexicans, the State Department noted.

"U.S. citizens have also been victims of random shootings on major highways outside Mexico City, Nuevo Laredo, Tijuana and other areas throughout Mexico," the warning said.

Laredo officials and anti-drug agents disagree over whether the drug violence has spilled over to the U.S. side of the border.