wrong branch, right move
One axiom of good cardplay is this: every decision is a new opportunity to make the optimal play. No matter how bad your previous decisions were and how bad of a spot they landed you in, you still need to make the best choice given the options available to you.
Example: you and your partner have a bidding disaster in bridge, because your partner does something dumb during the auction. Instead of landing in a contract of 4 spades, you are now the declarer in a contract of 3 Notrump. Had you correctly landed in 4 spades, you could easily make the contract and score 620 points. But here in 3 Notrump, you are likely to not make the contract and you are going to lose points. All you can do at this point is try to lose the minimum number of points. If you cry and moan and play the hand terribly and only make 6 tricks and lose 300 points, you can certainly scream at your partner about his bidding. But if you forget about the bidding disaster, focus on the hand, play it brilliantly and only lose 100 points, you can still get mad about the bidding later. So you focus, play it well, take 8 tricks, and only lose 100 points. What's the difference? Well, 200 points.
Example 2: you are playing tournament poker. It folds to you one off the button. You have noticed that the player on the button and both the blinds are super-tight senior citizens who are folding almost all their hands. Your adjustment has been to blindly raise 100% of the time it folds to you, to steal their blinds. You look at your hand and it's 82o. But you still raise to 2.5 big blinds. Surprisingly, the button doesn't fold, but instead reraises you to 8 big blinds. You look up and realize the senior citizen that used to be sitting there must have been moved to a different table, because now it's Phil Ivey. You have made a mistake by opening this hand. But that's over. Your only decision now is what to do facing this in-position 3-bet from a world-class player while holding 82o. You could call or raise. But if you are smart, you will fold. That's the optimal choice.
In both of these cases, it would be silly to say the hand was played well. Taken as a whole, the errors on the bridge hand cost us 720 points, and the error on the poker hand cost us 2.5 big blinds. But both of the mistakes were made on early decisions in the hand, which put us down a branch of the tree where we were destined to have a negative expected value. Once we were on those branches, we made a pair of good decisions, playing optimally and minimizing the losses. It would be silly to criticize those decisions in and of themselves. They were great decisions! In the poker hand, the classic discussion among friends afterwards will start "I would have folded initially, but as played, good fold."
Politics is orders of magnitude more complicated than bridge or poker, so evaluating decisions is a lot tougher, and clear answers almost impossible to arrive at. But you still need to bring the same mentality; even if you are down the wrong branch of the tree, you can still make optimal decisions.
Trump's current exit strategy from the Iran war is, in my view, a case of this. Because of the partisan dynamics, it's very hard for anyone to take the following position: the war was probably a bad idea, it didn't achieve it's objectives, but Trump may very well be getting the best deal possible to end it. Trump and his supporters will never say this, because he is undoubtedly going to try to portray the war itself as a success. Opponents of the war, likewise, are going to say the deal to end the war is bad because the war itself was a mistake that didn't go well.
In my view, it's completely plausible that Trump is getting the best deal possible to end the war, given where we are. Or not. But how we got down this branch of the tree no longer matters. All Trump can do is try to get the best deal possible at this juncture. He fucked this up pretty badly---we are almost certainly not winning this hand in the bigger picture---but that can't tell you whether the deal itself to end the war is good or bad. It's a separate question. And the reflexive impulse to judge the final decisions based on the quality of the earlier ones is a mistake. I feel like wars are particularly susceptible to this problem of evaluation; every exit decision is judged not on the immediate merits, but on the wider context of the entire conflict.
It's very difficult---in cards or politics---to do this. Your partner screwed up the bidding, you didn't realize who was on the button in the poker hand, Trump started a dumb war. In every case, you are now faced with decisions that, from the meta-view, can only be less wrong or more wrong. It's disheartening and frustrating. But it's vital, in the long run, to choose less wrong. And to evaluate less wrong decisions as good ones.