The United Stated of America, not to mention other NATO countries, is not now ready to wage war against Pakistan.
U.S.-Pakistani relations have been strained to the limit after another airstrike was carried out in Pakistan by American helicopters. Pakistan has blocked the cargo transit for NATO forces in Afghanistan and its companies refuse to supply fuel to NATO officials. Additionally, Islamabad has demanded that over the next 15 days, Washington clear the Shamsi airbase in Baluchistan province, from which the CIA launches Unmanned Aerial Vehicles to strike the Taliban.
This isn't the first escalation of tension in the relationship between "the allies in the war on terror," but each of them becomes harsher, which, actually, is quite logical.
In the '80s, Washington and Islamabad (and also Riyadh) together created "al-Qaida" to fight the Soviet forces in Afghanistan. The same holy trinity created the "Taliban" in the '90s to stabilize that same Afghanistan, which had been submerged in complete chaos after the withdrawal of Soviet forces.
Because one task after another was completed, Washington simply abandoned its projects because they weren't necessary anymore. As a result, al-Qaida changed things up and started to beat its creators. And the Taliban gave refuge to their closest ideological allies with great pleasure.
As far as Islamabad goes, the control over Afghanistan is vitally important. This country is being viewed by the Pakistani authority as a strategic back door in case of war with India. And the Taliban, which was created by the Pakistani intelligence service on Saudi money, is the primary instrument of such control. This is why Islamabad can't leave the Taliban and is only pretending to fight against them. The inevitable withdrawal of the Americans is awaited there, after which the Taliban will take over power in Kabul again with Pakistan’s full support.
In Washington this was all well understood a long time ago, and yet Washington continues to play-act, calling Pakistan an "ally in the war on terror." This is first explained by the means of transit, which go primarily through Pakistan. Secondly, it is explained by the fact that the U.S., not to mention other member countries of NATO, is not ready to wage war against Pakistan.
Pakistan has nuclear weapons and western countries and their armed forces will never take the risk of getting hit. Additionally, Pakistan has large and powerful non-nuclear armed forces. The Europeans won't be able to handle them. The U.S., of course, could beat Pakistan. However, to do this it would need to increase its contingency several times over — and not just quantitatively, but also qualitatively.
The current U.S. and NATO forces in Afghanistan are carrying out a counter-insurgency war exclusively. They have hardly any tanks (the U.S. doesn’t have any at all), very few of artillery, no Air Defense System (neither on the ground, nor fighters). The amount of strike aircrafts for such a war is also not enough. Admittedly, all that would have to be transported to Afghanistan, which would take too much time and would require a lot of money.
Apart from that, in this case it will be understood in Islamabad that the war being prepared is against Pakistan. At most, Pakistan could strike the U.S.-NATO military contingent, which in its current state wouldn’t be able to repulse it. At least, it will completely, finally and forever block the passageway through its territory. Therefore, the Americans will have to transfer their military planes through Russian air space and wheel their Abrams tanks on Russian railways.
Objectively speaking, Russia should in every way have supported the Americans’ defeats of those powers, which they themselves had created. Pakistan is one of our main potential enemies. Unfortunately, Moscow's actions are so irrational that there is no legitimacy to be expected from them. Russia, which is interested in the success of the U.S.-NATO operation in Afghanistan even more than its participants, has been trying to sabotage the operation for a long time. Even now, after a lot of grumbling, it has agreed to the transport strategy, but only of non-military cargo. One can only imagine how much noise our multiple paranoiacs would make if American tanks and IFVs were to go through Russia! How many crazy people would run and lie down on the rails in front of those trains.
On the other hand, the "accidental" American strikes on Pakistan, which are becoming more frequent, give the impression that the U.S. is provoking Islamabad to strike first. It has not been excluded that, for that sake, the U.S. is ready to sacrifice its contingent in Afghanistan in order to completely destroy Pakistan, which has been an ally of Beijing for half a century. And recently, a Chinese-Pakistani convergence, including in the military and military-technical fields, has been progressing at a fast pace. Having destroyed Pakistan, the U.S. will thereby kill two birds with one stone. In a couple of years when large-scale military budget cuts take place, this would already be impossible.