Danger zone for Americans

BRIAN WILLIAMS, anchor: We're back now with a frightening look at the dangers facing American farmers and ranchers living under the constant threat of violence, in constant fear, all because of where they happen to live and work, along our nation's southern border with Mexico . NBC 's Mark Potter reports tonight in his award winning series of reports THE WAR NEXT DOOR .

Offscreen Voice #1: There's the bundle right there, a large narcotics load right under the helicopter.

MARK POTTER reporting: South of the Texas border, on the Mexican side of the Rio Grande , a surveillance video of what police say are smugglers loading illicit drugs bound for the United States .

Offscreen Voice #2: One, two, three, four, five, six, seven bundles.

POTTER: Day and night , the drugs are floated across the river in rafts and are then often carried across private property in the US, where increasingly American farmers and ranchers along the border say they and their workers are being confronted, even threatened by armed Mexican traffickers.

General BARRY McCAFFREY , Retired ; It clearly has intimidated US citizens, who in many cases just don't believe they're safe on their own land in their own country.

Offscreen Voice #3: They went off road, avoided the spikes.

POTTER: Fearing retribution from Mexican smugglers, this farmer would only speak on camera with his face and voice disguised. He says he was told by a federal agent to protect himself.

Unidentified Farmer: One of them recommended that I look into buying a bulletproof vest.

POTTER: While you're farming?

Farmer: While I'm farming.

POTTER: The problem for farmers and ranchers isn't just confined to those right on the border. Also affected are land owners miles inland, where smuggling is still a huge problem.

Dr. MIKE VICKERS: How does this look?

POTTER: Veterinarian Mike Vickers leads a group of Texas land owners who work closely with law enforcement. They worry about Mexican drug and immigrant smugglers threatening their homes and trampling their land.

Dr. VICKERS: This fence was cut, no question. It was cut and pulled up.

POTTER: With hidden cameras, they've documented waves of smugglers crossing private property.

Dr. VICKERS: You know he's carrying at least 40 pounds of drugs in that backpack. We suspect cocaine.

POTTER: Vickers says many ranchers have moved their families off their land for safety, while others arm themselves.

Dr. VICKERS: This is happening on American soil. This is a war zone here. There's no question about it.

Offscreen Voice #4: Right beside the helicopter there's another crew, about...

POTTER: The Obama administration and some local officials dispute the war zone claim; but with Mexican traffickers not letting up, US land owners are asking for more federal protection at the front door to their own country. Mark Potter , NBC News , along the Rio Grande .