Cave fighting costs you quite a bit. The enemy locations are largely unknown, and most times the entrances are booby trapped. So your choices are to blow them up in places or try to infiltrate the caves. In some situations, there’s no reason to go climbing down into caves when you can call in air strikes instead.
Daisy Cutters were actually developed in Vietnam to clear landing zones for helicopters. The Vietcong would wait for helicopters to land and fill up with troops, and then they'd try to shoot them down. A Daisy Cutter would blow out a football field-sized area, clearing the jungle and leveling the trees. It has always been employed against hidden troops, and its advantage is a sudden overpressure that kills people.
Against the Japanese, we used napalm. We used to use white phosphorus, too, which burns at 3,000 degrees and is just a nasty weapon. What we have in Tora Bora are concussive munitions. Frankly, if you're dead you're dead, but it's much more gruesome to burn someone to death.
The bunker busters and Daisy Cutters create a shock-wave kill instead of a burn. A bunker buster is huge, about the size of a Buick, and it's built to go in end-up where it drives itself into the ground to penetrate 10-12 feet before blowing up. These worked well in first Gulf War to decimate the underground airplane hangars. They just penetrated the concrete and blew up the hangars in sort of an impromptu mining.
To coordinate air strikes at the caves of Tora Bora, we needed the Afghan fighters on the ground to draw enemy fire. Sounds like a great job, huh? You're taking a risk sending your assets into the caves, but this tactic is nothing new. In Vietnam, we had what we called "tunnel rats." These guys went into holes and tunnels head first looking for enemies. They were armed with a flashlight and a pistol because that's all they had room for.
Now we have the advantage of fiber optic vision to look in holes and around corners from a safe distance, and if we are up close and personal, at least our guys have night vision capabilities. I would assume the Afghan fighters had that sort of equipment at Tora Bora. It's really a huge adjustment to go from broad daylight into pitch darkness. So you always strap on night vision goggles before you go inside a structure like a cave.
The next thing you do is roll a grenade into the hole. Remember, you're entering a cave where the enemy has had a long time to sit and think about your coming to visit. So he has the advantage of time and has probably installed wires and traps. If you're after a VIP, you'll roll out a flash-bang concussive grenade. You don't want to tangle with an enemy who is fully aware and ready to fight. You always go in on your own terms
From an interview with US Army Staff Sergeant Dan Snyder