But interviews in recent days offer a fuller picture of American involvement, and show that it is far deeper than discussed in public and more instrumental to the fight than was previously known.

From the air, the United States is supplying much more firepower than any other country, with American bombing missions increasing to 107 on Sunday, from 49 on Thursday. Besides taking part in the airstrikes, the American military is taking the lead role in gathering intelligence, intercepting Libyan radio transmissions, for instance, and using the information to orchestrate attacks against the Libyan forces on the ground. And over the weekend the Air Force quietly dispatched two of its most fearsome weapons to the operation…

For the Americans, six tank-killing A-10 Warthogs that fire laser-guided Maverick missiles or 30-millimeter cannons arrived on the scene this weekend to join the fight. The United States also deployed two AC-130 gunships, lumbering aircraft that orbit over targets at roughly 15,000 feet, bristling with 40-millimeter and 105-millimeter cannons. The gunships’ weapons are so precise that they could operate against Libyan forces in cities, which so far have been off limits for fear of civilian casualties.