WASHINGTON — The towering trucks that give U.S. troops the best protection against roadside bombs and enemy bullets also make them vulnerable to routine hazards such as sharp turns, rutted roads and rickety bridges.

Five deaths caused by rollovers and dozens of other accidents in Iraq and Afghanistan have led U.S. military leaders to warn troops to be smart behind the wheel, according to military documents obtained by The Associated Press and accident reports released under the Freedom of Information Act.

The message is especially relevant in Afghanistan, where a resurgent Taliban has boosted demand for these steel cocoons, known as MRAPs. Due to the country's mountainous terrain and unpaved roads, officials will send nearly 800 more RG-31s, the smallest of several different MRAPs the military now uses.

Yet even at a comparatively nimble 9 tons, the RG-31 is not immune from tipping. On June 29, three Green Berets drowned when their vehicle rolled into a canal in Afghanistan. The accident is under investigation.

The MRAPs — the military's acronym for "mine-resistant, ambush-protected" — get high marks from commanders for protecting U.S. personnel from enemy attack. Close to 7,000 of the vehicles are already in use in Iraq and Afghanistan and the Pentagon is buying at least that many more.

And despite their bulk, the MRAPs have power steering, air brakes and quick acceleration. These features can lull drivers into thinking they're just handling a bigger version of the smaller and more agile Humvee.

Don't be fooled.

"This ain't your father's Oldsmobile," says the June edition of "Safety Corner," an internal newsletter published by the Marine Corps Center for Lessons Learned in Quantico, Va.