"preparing perfectly for the last war and ignoring developments that have happened since"
Indeed, any modern conflict is now guerilla and propaganda based. The greatest threat to the West, ISIS and their ilk, cannot be defeated like you would a traditional enemy. When we go screaming into Syria and start bombing places, we may kill a few of them, but the fact that we are also killing innocents gives them far more strength than what the people we killed provided. Their entire recruitment campaign is "Look at those evil Westerners, coming in and killing innocent women and children, we must stop them before they kill your wives and children!"
What we should be doing is to take some land, heavily defend it, and help them build a country founded on proper Western Ideals (Give them the framework for a Secular government, plan out a properly regulated capitalistic economy, provide proper laws granting equal rights to everyone). Allow anyone to join this country and help build it out so long as they support the nation's ideals, thereby ending the refugee crisis and cutting off ISIS's stream of recruits.
Secular would end all these conflicts where one religious sect has power and starts discriminating against the other (Which is the primary cause for the Arab Spring), a properly regulated form of capitalism would end the massive wage gap that is causing so many problems in the rest of the region (like what happened / is happening in Yemen), and of course equal rights laws to reinforce the secular government. Ending religious discrimination would gain support from the Kurds and Lebanon. The vast majority of the civilian population in the region are much like us westerners: They don't care who is in charge, so long as they are able to go home to their spouse and children and enjoy a nice meal together, and mostly importantly, know that they could do the same for every day for many years to come.
Set up a program where former ISIS soldiers (who aren't responsible for war crimes) are given enough money to bring their family for a little while and a two-bedroom apartment in exchange for whatever weapons and intelligence they can steal on their way out. Many of ISIS's soldiers joined because it was the only thing they could do so they can buy food for their families since every other employer has been ran out of town or killed.
My girlfriend works for a relief organization that helps re-settle refugees and soldiers that have defected from the various terror groups. The thing that they really want isn't just a couple of rations, but a residence to call their own and a way of ensuring that there will be food in the fridge, many of them were willing to work in the worst jobs imaginable just for that opportunity. The vast majority of the men are skilled and ready to enter the workforce, Syria was a functioning country complete with farmers, construction workers, doctors, engineers, shopkeepers, and everything else a country would need.
Hell, the US could solve their "illegal immigrant problem" by bringing them into the country and letting them work the jobs that "Dem ee-lee-gulls took from 'ard workin' 'muricans"