More like Calvinball?
Pakistan's policy has been all over the map, with several cycles of "leave them alone and it will all go away" and "we're going in shooting." While I'm sure there has been pressure from the outside, if U.S. pressure was the whole story I'd like to think the policy would probably have been a lot more consistent.
Pakistan has nuclear weapons, and the western part of its country has gone radical Islamist and would like to spread that philosophy around. Hardball is called for somewhere along the line, and if we weren't putting some kind of pressure on Pakistan, I'd bet India, Russia, and a few others would gladly step into the breach.