Sorry, but you need to get realistic. The United States cannot eradicate evil. That is what you, and many politicians think and want you to believe.
You can’t use our military for that!
If our national security is threatened, then you use the technological advantage of hi-tech warfare from above to instill damage accordingly. Or use covert operations in concert with loyal local on the ground forces, but COMBAT operations should be strictly for military objectives - not as a substitute to undertake prolonged subsidized ‘nation-building’ schemes where the local majority is incapable of sustaining themselves.
Simply not being able to “eradicate evil” does not mean you stand back and let it multiply. Saying that a nation (especially one founded on the principles the USA was founded upon) cannot “eradicate evil” also implies a lack of faith in God, with all due respect; even FDR finally realized that his human efforts were futile and that he and the nation needed to turn to God to win WWII.
That said, I agree that the “strategy” in Iraq was all wrong, and deliberately influenced by liberals to bring about a negative outcome for the USA (to wit, defining recreating Iraq as a Shi’ite Islamic Republic as “nation building” and in any way legitimate).