From this morning’s New York Times…

The explosion that killed 14 marines in Haditha yesterday was powerful enough to flip the 25-ton amphibious assault vehicle they were riding in, in keeping with an increasingly deadly trend, American military officers say.

In recent months the roadside bombs favored by insurgents in Iraq have grown significantly in size and sophistication, the officers say, adding to their deadliness and defeating efforts to increase troops’ safety by adding armor to vehicles.

The new problems facing the military were displayed more than a week earlier, on July 23, when a huge bomb buried on a road southwest of Baghdad Airport detonated an hour before dark underneath a Humvee carrying four American soldiers.

The explosive device was constructed from a bomb weighing 500 pounds or more that was meant to be dropped from an aircraft, according to military explosives experts, and was probably Russian in origin.

The blast left a crater 6 feet deep and nearly 17 feet wide. All that remained of the armored vehicle afterward was the twisted wreckage of the front end, a photograph taken by American officers at the scene showed. The four soldiers were killed.