So, your advice is, the US government should be able to predict the future. Avoid "pointless" conflicts, but also intervene early, when no real bloodshed has occurred yet, to prevent larger conflicts. Tell us exactly how that is done.
No. I am arguing for avoiding war if at all possible, and if going to war, then limited wars with limited aims. See for example the first vs the second Gulf Wars. The US leadership at the time of the first explicitly rejected "all the way to Baghdad" as, Dick Cheney said, it would lead to a lengthy involvement in a civil war. They kicked Iraq out of Kuwait and then sat there. The goal was to not have Iraq bother any of its neighbours any more, this goal was well-achieved.
The second Gulf War was and is an unlimited war with unlimited aims. Neither the US government and military, nor any of the lefties who are suddenly in favour of war in the Middle East now that the orange buffoon is against it, can tell us: exactly when will we have won and can go home? And if we don't win, exactly what price are we willing to pay before we call it quits?
Avoid war if at all possible, and if not, then limited war with limited aims.
It was not necessary to go to war in Afghanistan at all since
the Taliban offered to give Bin Laden up to an international tribunal. And once at war, it was not necessary to occupy the country. As for Iraq, that was nothing but a war of aggression, as much as Germany's invasion of Poland was. And the US's presence there has only made the conflict longer and worse. Likewise Syria, which without Western involvement would have crushed the rebellion in a year or so. And Libya and Ukraine simply show what it means to trust Western promises, and serve as an example to ensure North Korea should never give up its nuclear weapons.
In 1936 Germany remilitarised the Rhineland (correction: it was not 1934). This was a violation of the treaty of Versailles and thus was a legitimate cause of war. And it was accompanied by Nazi rhetoric about conquering Europe, which Hitler had written a whole book about in 1923. It doesn't take a crystal ball to see that if someone says he will do A, B and C, and he has now done A and B, that C will soon follow.
Avoid war if at all possible, and if not, then limited war with limited aims.