It was a tour of public lands with splendid scenery, a glib guide – and lethal firepower on hand just in case.

The tour last week – to Quitobaquito Spring at Organ Pipe Cactus National Monument south of Ajo – was guarded by federal officers armed with assault rifles and other weapons.

Why?

“It’s because of the perception that exposure to human and narcotics smugglers is a bad thing for the visiting public,” said Matthew Vandzura, chief ranger at the monument on the Mexican border.

Sardius Stalker, a seasonal park ranger who led last week’s tour, put it another way: “It’s like going into a bad neighborhood” where protection by “armed escorts” is essentia