"strong economic and strategic motive" behind Afghanistan? They did it to get Bin Laden basically.

America are like a slightly corrupt and violent world police.

So they invaded Afghanistan to grab a Saudi national hanging out in Pakistan?

Mostly https://en.wikipedia.org/wiki/Afghanistan#US_invasion_and_Is...

Apparently the invasion was Oct 2001 and Bin Laden hiked over into Pakistan in Dec 2001

I think it had something to do with 9/11 being an act of war from Afghanistan against the US. Nations are responsible for the actions of groups inside their borders against other nations.

It was not an act of war since Afghanistan didn't have an official government - in practice the Taliban ran things - but the attacks were carried out by the Al Qaeda which was spread over the Middle East. The Taliban might have been sympathetic to it but they were not actively supporting them or had any official collaboration with them.

Acts of war are between nations, not between governments.

I hope you see where the problem with this is - the US had an enemy in a supranational organization, the Al Qaeda, which resided in many countries including Afghanistan.

The government of said country was unfriendly but not actively hostile to the US and on good terms with AQ, but not outright allies. This could've been said to apply between many Middle Eastern governments and radical groups at the time.

The US decided to invade, and antagonized the formerly unfriendly Taliban to become actively hostile.

The US managed to temporarily win over the Taliban but failed to permanently displace them.

AQ leadership, including Bin Laden moved out of the country almost immediately.

The 'war on terror' went on almost without end, then Bin Laden was killed a decade later, in a different country the US didn't declare war on, thanks to US special force action.

While AQ got weaker, ISIS got stronger (honestly I don't follow ME insurgent groups that closely, I wouldn't be surprised if this was a rebrand/reorganization in part).

So the US-initiated invasion totally failed to reach its stated result while leaving a huge collateral in its wake.

Strategic motivation? If one assumes the US is going to be globally involved, yes, but that's begging the question.

Economic motivation? Not so much now, with the US being a dominant oil producer, and with petroleum itself losing importance. Even then, it's questionable if this could justify the full cost of the US military.

I think the original motivation was two fold: it was a combination of some sort of moral obligation to defend the "free world" from authoritarians, and (after WW2) a desire to keep small countries (and recent WW2 enemies) from deciding their only option for defense was their own nuclear deterrent.

I don't see much evidence that's the US wants to defend the world from authoritarians. Some of their closest allies are authoritarian countries.

Expansionist authoritarians, which in the post war world was communists.

Why would the world need defending from non-expansionist authoritarians?

Maybe. They seem to actually like expansionist authoritarians now. Evidence being the Russia Ukraine peace effort.

Another thing the US did in the post-war world was apply economic leverage to dismantle European empires. This can also be viewed as defending nations against external coercion.