Not for the first time since he began a six-week war with Iran five months ago, U.S. President Donald Trump finds himself stuck.

He told the world just recently he would unleash a hell yet unseen on Tehran, because Iran’s leaders clearly hadn’t been hit hard enough to understand the futility of resistance. Now, he has stood down, apparently after being advised he has no good military options.

Two questions arise. First, why can’t U.S. can’t impose its will on Iran, a vastly weaker military power, even after obliterating its conventional naval and air defenses? And second, how can Trump fail to understand this incapacity to the extent that he’s having to be restrained from fulfilling one popular definition of insanity — doing the same thing over and over in the expectation of a different result?