This year, bomb attacks on coalition troops in Afghanistan have spiked to an all-time high, with 465 in May alone, more than double the number in the same month two years before. At least 46 American troops have been killed by I.E.D.’s this year, putting 2009 on track to set a record in the eight-year war.

I.E.D.’s have been even more deadly for Afghan police officers and soldiers. At the current rate, I.E.D. attacks on Afghan forces could reach 6,000 this year, up from 81 in 2003, an American military official said. In early July alone, nine Afghan police officers were killed in two bomb attacks in Logar Province, south of Kabul.

With few paved roads, Afghanistan is even more fertile territory for I.E.D.’s. than Iraq, where hard pavement often forced insurgents to leave bombs in the open. Not so in Afghanistan, where it is relatively easy to bury a device in a dirt road and cover the tracks.

Even when I.E.D.’s do not wound or kill troops, the threat restricts and complicates the movements of coalition forces.

Image A Marine ran to safety as a homemade bomb exploded Monday in Helmand Province, Afghanistan; the blast killed two others. Credit... Manpreet Romana/Agence France-Presse — Getty Images

American convoys often must wait for bomb-detection teams that move at three miles per hour. Helicopters are limited, and most troops travel in mine-resistant, ambush-protected vehicles known as MRAPs, which are lumbering and hard to maneuver. Though heavily armored MRAPs are effective in shielding soldiers from explosions, two turret gunners died recently when one flipped over after hitting I.E.D.’s.