NATO is a defensive alliance, so there has to be a provocation for them to act.

Not necessarily see their previous involvement in conflicts. What kind of defence was nato doing in Afghanistan

The attack on Afghanistan was literally an invocation of NATO's Article 5, the only time this has happened:

"Article 5 provides that if a NATO Ally is the victim of an armed attack, each and every other member of the Alliance will consider this act of violence as an armed attack against all members and will take the actions it deems necessary to assist the Ally attacked."

So, the 9/11 attacks were considered an armed attack on the United States, and the alliance deemed it necessary to overthrow the Taliban in order to prevent Al-Qaeda from perpetrating similar attacks again.

One can disagree with the rationale behind the decision, or the cost-benefit ratio. But it did follow the protocols of the alliance.

I think it's very naive to think that us invaded afganistan to protect itself or prevent similar attacks. It was pure irrational vengeance by bush. It may follow their protocols but by no means you can consider invading and occupying a foreign country for 20 years as defensive. In effect u cannot call nato a defensive organization by their involvement in wars where no defense was required

You're looking at it in retrospect, but decisions to involve NATO in responding to an attack on a member aren't made with the benefit of hindsight.

> us invaded afganistan to protect itself

... is a very different thing than ...

> occupying a foreign country for 20 years

When NATO invaded the towers were still smoking, the war-on-terror intelligence apparatus had yet to be built, and we (I) had no idea whether another attack was forthcoming. It felt pretty damn reasonable at the time.

Whether you believe it was right or wrong to get involved in Afghanistan, NATO’s involvement there (not Iraq) was a direct response to the 9/11 attacks and the government (at the time) of Afghanistan’s refusing to allow the US to directly target the group responsible that was based there.

Their response was invading a country for 20 years, you can hardly count it as defensive. Invading afghanistan was always about more than 9/11, it was far more than that.

The difference between a defensive response and an offensive is not how long it lasts.

The idea was that the Taliban was harboring Al-Qaeda, so NATO members were assisting the US in response to the 9/11 attacks.

Apparently, the department of defense doesn't need a provocation for them to act.

Like in Libya in 2011? In Kosovo in 1999? This fairy tale has been dead for decades now.