It has taken the Trump administration just two months to race through all five years of the Johnson administration’s Vietnam policy: entry, escalation, frustrated stalemate, and negotiations. Now, it’s on the Nixon administration’s turf: first blustery threats, then gradual realization of the need to extricate via an unsatisfying deal. If this pace holds, the intervention in Iran should be over in another few months, by which point the recriminations will already have begun. Of course, no historical analogies are perfect, and there are many obvious differences between the conflicts in Iran and Vietnam: different regions, different ideologies at play, a much shorter time frame, no U.S. ground troops or draft, no change in administrations, advanced military technology, and more. Still, there are notable symmetries in the structures of the two conflicts. And the same is true of the war in Ukraine, which has a structure symmetrical to that of the Korean War.…