Further to the post by Anony Mous, you have to wonder about the effectiveness of aerial bombardment. It would seem that it has seldom lived up to the expectations of the air commanders.
Between the two world wars, there were those who thought that aerial bombardment was going to win wars all on its own, thus making all the world's navies and ground forces obsolete (e.g. Giulio Douhet's 1921 work The Command of the Air). In reality, though, carpet bombing of population centres (such as London in 1940) failed to collapse civilian morale - possibly even causing it to stiffen. Also, despite an intensive bombing campaign by the air forces of Britain and the USA, German production of armaments actually kept on increasing during the years 1942-1944.
That aerial bombardment during the Vietnam War was largely ineffective was certainly not due to lack of quantity!
Between 1964 and 1975, US and Allied air forces expended 7.5 million tons of high explosive ordinance on Indochina. This was more than twice the total amount (3.5 million tons) of bombs that the Allies dropped on the Axis countries (both in Europe and in Asia) in all of WWII. In Laos, this effort failed to cut the infamous "Ho Chi Minh Trail", and in Cambodia, it made what was already a difficult situation much worse. (In Vietnam, it would seem to have been very much a blunt instrument - most notable for inflicting horrendous casualties on civilians)
Altogether, yet another case of unrealistic expectations being made of aerial bombardment.