One organisation that is hardly discussed regarding the Mumbay attacks is Pakistan's army. It is a parasitic state within the state that owns lots of land and other wealth. The main reason the Pakistani state is so weak is exactly because it doesn't have effective control over the army.
As the ISI is a part of the army establishment the Pakistani army is very much responsible for the Mumbay attack. Not that the army is a monolithic organization that stands as a whole behind the attack. It is rather a divided organization that is united by common army interests. From that point of view any conflict is welcome - as it will bring more money and power to the army.
The challenge to both the US and India is that it is in their interest to make Pakistan a normal country with a less prominent role for the army. Yet their actions risk to have the opposite effect. An indiscriminate Indian attack might unite Pakistan behind its army. US military aid may bring some action against the Taliban. But at the same time it strengthens the army as a whole. And as a whole the army has no interest in seeing the Taliban or the Kashmiri and Islamic terrorist organisations disappear.