NATO has as its interests the security of the member states, it is as simple as that.
https://en.wikipedia.org/wiki/Coalition_of_the_willing
The really bad part is that they were acting during the 'first installment' against people that weren't part of the attack on the United States to begin with (it was essentially a pretext), and the second time they outright lied about the intelligence regarding the WMDs (of which there already was conflicting data collected by the UN weapons inspectors).
NATO’s own resources are essentially office buildings, computer and communication systems, bureaucrats, and seconded military planners. The US didn’t need them for the Iraq War, although it would have liked to have had them involved, because of what that would have meant politically/diplomatically/symbolically.
Despite claiming a broad “coalition”, only three countries actually contributed fighting assets to the initial US invasion - the UK, Poland, and Australia - only the first two are NATO members, and Poland at the time had only recently joined (only 4 years prior). 3 more NATO members (Netherlands, Italy and Spain) provided non-combatant support. I don’t see in what meaningful sense it could be said to be something NATO did.
More NATO members joined in the occupation forces after the initial invasion. But that was never an official NATO operation because those require unanimous approval, and certain member states (most notably France) were always opposed to that.
NATO eventually did become involved in Iraq - training the new Iraqi government’s military. But no fighting ever happened in NATO’s name.
NATO was very careful to obtain requests from the UN in both cases, resolutions 1244 and 1973.
How is Putin ceasing to throw Russia's unwilling and unwitting armed forces onto Ukraine not easy?
"The treaty was created with an armed attack by the Soviet Union against Western Europe in mind, but the mutual self-defense clause was never invoked during the Cold War."
After WW2, it became clear that a new world order had emerged around what would be called "First World" (US-led countries members of NATO) and "Second World" (Soviet Union-led communist countries members of the Warsaw Pact). The "Third World" were non-aligned countries, often confused with "poor countries".
The roots of the current crisis trace back to these power structures. The fall of the Soviet Union and the rise of China could be seen as the beginning of new alignment, but so far, we haven't seen it fully taking shape (China is certainly working on it). Russia, while nowhere near its Soviet Union peak, remains a military superpower and the owner of vast natural resources.
Russia's current role in the world is unstable - there is a dissonance between its hard power and its actual influence in world matters. It doesn't accept being relegated to a weak geopolitical player, and the invasion of Ukraine is part of an attempt to assert its position in the world.
And they just changed again.
Putin believes that the "Soviet Union" is simply another name for Russia, the name of a particular phase of Russian history.
In his mind, the ex-Soviet states were all part of Russia, and their people were Russian–Ukrainians and Lithuanians and Georgians are not neighbouring foreign nationalities, they are Russians, traditional Russian ethnic minorities just like Chechens or Tatars or Tuvans. He views their independence in the breakup of the USSR as a historical mistake, for which he blames the Communist leadership.
He wishes the Communists had never introduced the idea of a "Union of Soviet Socialist Republics" because he believes it planted the seeds for the breakup of Russia–yes, Russia, since to him the Soviet Union was just another name for Russia–in 1991, and his current invasion of Ukraine is an attempt to partially reverse that breakup – even though he probably doesn't plan to annex the whole of Ukraine in the near-to-medium term, installing a puppet government in Ukraine which will promote Russophilia and Russification would bring Ukraine back into the Russian fold, and might even eventually lead to full annexation further down the line.
> Since then, however, NATO has revived admirably. Under President Joe Biden America sounded the alarm about Russia’s build-up and co-ordinated the Western response. “Putin has single-handedly given NATO a vitamin injection,” says Wolfgang Ischinger, chairman of the Munich Security Conference, an annual transatlantic talkfest that begins on February 18th. NATO’s three decades of angst about its role after the end of the cold war has been dispelled. Having performed “out of area” operations in the Balkans and counter-insurgency in Afghanistan, it is going back to basics: the territorial defence of allies. The theological rivalry between institutions in Brussels over whether the EU should have an autonomous defence capability has for the moment been stilled.