"Do something about this, or I will."

I can't prove it, but I think the threat comes from the US. The Paki gov already is reliant on US aid for survival (or they wouldn't bother doing anything at all for us). They are in an almost constant state of war with India, so I don't think its them. China and Russia aren't mature enough states to realize that just because your rival is bogged down doesn't mean you might not inherit his problem yourself someday, a lesson we seem to need to relearn ourselves every now and then.

The only other possible player is Iran, a Shia, non-Arab state who thinks the Afghans are all a bunch of illiterate tribesmen led by wacko Sunni Arab extremists. Not likely. The Iranians fear the potential of Al-Quaeda and the Taliban to infect their own country. That's why they cooperated with us after 9/11 until the "Axis of Evil" speech.

Again, I can't prove it, but I think the threat comes personally from Obama. At least, the timing leads me to think so. It's part bluff, after all, what can we do except let Pakistan fall to the extremists? That does us no good at all. It's a high risk strategy, but I think the one thing we are learning about Obama is that he is not afraid to take risks.
In fact, I'm starting to get impression of him as a quiet and deliberate thinker who, when he finally makes up his mind, is capable of doing anything without the slightest hesitation.