Overwhelming Afghanistan and invading Iraq are hardly comparable to engaging in an act of war with a country of a billion people.
Leaving aside that Pakistan has nowhere close to 1 billion people, I have to say that removing a couple of nukes hardly seems comparable to directly or indirectly killing hundreds of thousands of people.
It will piss off alot of people, true, but if Pakistan implodes, there are no good options when it comes to their nuclear weapons. Having them removed by the US might be one of the less dangerous ones, and might even be supported by parts of the current powers in Pakistan.
All this is of course pure speculation.
India/Pakistan damn near came to war several years ago and there are, unconfirmed AFAIK, reports of nuclear weapons being released to theater commanders. Meaning, the world hovered on the brink of a nuclear exchange¹ with the 'hold' being the least stable theater commander.
India has continually repeated they think terrorist attacks in India are being supported and financed by the ISI. Upon the military and political leadership concluding Pakistan's nuclear arsenal is under, or going to be under, control of the ISI or their political allies a sufficient condition for a pre-emptive First Strike has been met.
¹ Jargon for a small scale nuclear war.
