Switch to Desktop Site  On Kosovo frontier, a mission chasing
'ghosts'  President Bush is due to meet US troops in Kosovo
tomorrow.  About these ads  Sgt. Mike Martinez shifts the rifle
slung across his shoulders, scans the tree line across the
valley, and listens to the early-morning bird song and distant
cowbells.  In the meadow below him, nothing moves. He checks his
Global Positioning System again, and shrugs. "That's why we call
ourselves the Ghostbusters," he smiles. "If there was anybody
here," he says, referring to their comrades' reports of eight
ethnic-Albanian guerrillas passing through, "they're long gone."
The sergeant's fruitless patrol - a long Humvee ride followed by
a long walk to search for guerrillas trying to slip across the
border into nearby Macedonia - illustrates the difficulties
facing the US troops in Kosovo, whom President Bush is due to
visit tomorrow.  "We're here for a peacekeeping mission, not
war, so the assets aren't here," Martinez's company commander,
Capt. Joe Ross, later