The CIA has long gauged the effectiveness of military assaults on Haqqani leadership on both sides of the border by their ability to use large bombs in eastern Afghanistan and Kabul. Haqqani attacks have not subsided over the years.
U.S. and other NATO alliance forces who make up ISAF, as well as U.S. Special Operations Forces, have long faced casualties from Taliban bombers trained by al Qaeda who attack troops with suicide vests, car bombs and pressure-plate IEDs.
Since 2001, 934 American troops have been killed and almost 12,000 wounded by IEDs in Afghanistan, according to the military's Joint IED Defeat Organization.
But massive truck bombs are rare -- and one carrying more than 30 tons of explosives would be unusual anywhere in the world, experts said. Some analysts questioned the Afghans' estimate of the explosives' weight but still acknowledged the size of the Gardez VBIED is extraordinary.