As he careered along the rock-strewn gulley towards his silver mine deep in the Sonoran desert of southern Arizona, Roger McCaslin first checked his bowie knife, then his pistol, and finally his Kalashnikov. From the road, he had already noticed that something was wrong. "The gate's broken and the door on the trailer's open. They've been here, I know it," he said ominously. "I just hope they've moved on - for their sake." Under the harsh sun, Mr McCaslin's black cowboy hat cast a shadow over his droopy moustache and a face so deeply creased that it resembled cracked saddle leather.Welcome to the Wild West 2005, where modern-day cowboys still guard their land from interlopers - but using AK47s and four-wheel drives instead of Winchester rifles and horses. Mr McCaslin's small mine sits on a knoll of red earth and scrub near the Mexican border. Like his 19th-century predecessors, he is sure there is money in "them thar hills" after a geological survey indicated there may be rich veins of silver. Today, however, he has other priorities. For the mine also sits in the middle of a network of trails used by heavily-armed Mexican trafficking gangs to smuggle people and drugs into America. Notoriously porous, the border has reached new levels of lawlessness this year as smugglers, known as "coyotes", have become increasingly brazen, willing to fire on anyone - from border patrols to the likes of Mr McCaslin - who gets in their way.
The political row about America's "soft southern underbelly" - bolstered by fears that terrorists may slip in through it - has led to growing support among Republicans for a radical plan to build a 2,000-mile steel and wire fence along the entire border. The Homeland Security Department says that such a fence would be a waste of money, however.
Meanwhile, in a high-profile campaign launched earlier this year, hundreds of volunteers flocked to Arizona from across America to join the Minuteman Project of civilian "monitors" patrolling the border to record illegal crossings. Denounced as "vigilantes" by President Bush and as dangerous amateurs by the United States border patrol (many of the volunteers carried legal side-arms), they have drawn further attention to the problems of border security.
Mr McCaslin, 50, says US patrols have increased in recent weeks as public pressure has mounted - and as he edged up the track towards his land, a helicopter swept repeatedly over a nearby patch of bush. Kalashnikov in hand, he strode up to the 1950s-style Airstream trailer home where he stays when working at the mine. He kicked open the door which swung on broken hinges. Clearly there had been overnight visitors: the interior had been ransacked, shelves pulled out, coffee and biscuits scattered across the carpet and the bed torn apart. They had already left, to the apparent disappointment of Mr McCaslin, whose regular job is as a wrangler (horseman) at a "dude ranch" where visitors saddle up for rides through the desert.
Not every day passes without confrontation, however. He recounted several gunfights with the "coyotes", including one occasion when he and his business partner came under fire at dusk as they barbecued steaks. "They started the war when they started shooting at us. One time, my partner definitely hit one of them. The guy got away, but I doubt he got far. His friends won't have taken him to hospital. They probably just left him out there somewhere," said Mr McCaslin, gesturing to the inhospitable terrain where rattlesnakes and tarantulas add to the dangers.
From his vantage point at the mine, he has watched long lines of illegal immigrants traipsing north through the desert, leaving their detritus as they passed. Discarded everywhere, in disused mines and beneath bushes, are the cheap clothes and bags that they abandon to travel faster and less conspicuously. Empty water bottles litter the landscape. Once Mr McCaslin found a 300lb stash of marijuana hidden in a hollow. "I called up the border patrol who came and took it away. Then that night I sat up here and watched the car lights of the coyotes as they searched and searched for the stuff. Boy, they must have been mad," he said with a satisfied grin.