If India ever goes after Pakistan in earnest, Pakistan will lose. I have no idea how the US will react, other than the State Department will condemn any action. This is what the State Department does. As for the remainder of those in D.C., the democrats will cry foul and demand India quit kicking Pakistan’s butts. Republican will probably remain quiet. But I do not expect anything other than an investigation and assorted arrests, coupled with a ‘back channel’ warning to Pakistan, if those who did this turn out to be from Pakistan.
You know, it wouldn’t surprise me if this was the work of the Red Mosque jihadists. They would have the most to gain from initiating a shooting war between India and Pakistan.