Nato has been thoroughly prostituted, and subverted. To wit-
The organization constitutes a system of collective defence whereby its member states agree to mutual defence in response to an attack by any external party.
... Article 5 of the North Atlantic treaty, requiring member states to come to the aid of any member state subject to an armed attack, was invoked for the first and only time after the September 11 attacks,
... The organization has operated a range of additional roles since then, including sending trainers to Iraq, assisting in counter-piracy operations[7] and in 2011 enforcing a no-fly zone over Libya in accordance with U.N. Security Council Resolution 1973.
https://en.wikipedia.org/wiki/NATO
Invoking Article 5 for these events is bullshit. 911, in particular, was a hideous atrocity- but it was not carried out by another State against a Nato member State- it was carried out by a terrorist organisation. It was a Terrorist atrocity, not an invasion. So the Article does not apply. This is not to say a fellow member state of Nato cannot assist the USA in a joint military action of course- but it does Not apply under Article 5 (or the somewhat weaker Article 4) of the Nato treaty. That is a bilateral agreement between States, not a Nato mandate.
Nato has become an extension of hawkish US foreign policy- not surprising really, because the US pays for and arms the lions share of it. It has gone way past it's original mandate (simply put, a defence club against Russia & the Eastern bloc), and the legality of it's actions are dubious at best. Currently it is being used as a tool to taunt and provoke the Russian Bear- I fail to see the benefit to Europe, that houses most of it's military hardware, and relies on Russia for it's energy supplies, in this.
I don't believe Nato should be disbanded- but I do believe it should have it's horns pulled in. It is a tool of our joint foreign policy, not the determinant of it.