Bagram Air Base, Afghanistan ? Strategically buried in the middle of dirt roads, packed in culverts and attached to trip wires, a heightened hidden danger awaits the thousands of U.S. troops pouring into Afghanistan to fight a tenacious Taliban.

The U.S. military expects a 50 percent spike this year in roadside and suicide bombings, which surpassed the number of similar strikes in Iraq during the spring. These types of bombs killed 172 coalition forces last year — and far more Afghan civilians — according to military figures.

“We don’t hide the truth from them. We tell them if you are going to be killed or injured in Afghanistan, it is probably going to be by an IED,” said Command Sgt. Maj. David Puig, 51, of Fort Lewis, Wash.

The dramatic rise in these attacks — and the insurgents’ skill in placing and camouflaging the bombs — complicates the U.S. mission as the Obama administration searches for a fresh approach against the insurgency with the appointment this week of a new commander, Lt. Gen. Stanley McChrystal.

Troops who have served previous tours in Afghanistan, when the Taliban insurgency wasn’t so violent, say they now confront far more improvised explosive devices, or IEDs.