I'll disagree with it on a number of points, but I believe you have about the only rational reason for being there. My points of disagreement:

The US is involved in nation-building, not assisting the police force of another nation. The US deposed the former government and then conducted voting which installed the US-backed puppet. Then the US tried to create a police force and army loyal to the puppet government and therefore the US. That is more political than policing.

The US is attacking what the US perceives as enemies of the US, not necessarily enemies of the Afghan people or Afghan government. In fact, the Afghan government, even though heavily dependent upon the US to stay in power, has repeatedly protested the American treatment of it's civilians and stressed the need to negotiate with what America perceives as enemies. The Afghans don't necessarily regard the Taliban as hostile, and neither do the Pakistanis.

When an army invades a foreign country to rid that country of elements hostile to the invading country, not the "host" country, that's called war, not policing. When that operation has gone on for 7 years with the hostile elements stronger than at the beginning, that's called failure. When the invasion creates more problems than it solves, that's called a disaster.

The actions in Afghanistan and Pakistan are destabilizing the entire region, including India. And the last thing the US would want is a failed Pakistan, which seems to be coming. We do not have enough troops to control much over there. And Pakistan is the worlds greatest nuclear proliferator. How long would they hold off on selling a nuke or two to someone who wanted one?

I think the actions over there are at present counterproductive, creating more chaos where chaos is the norm. And that there will be no way to "win", endless ways to lose, and lose very, very big.

And I can see where someone might think it's a "police" action. Makes some sense.

Arf