Bangladesh, Sept. 7 -- Power can protect a state. It can deter its enemies, expand its influence and give its leaders confidence. But power has a dangerous side effect: it can distort judgment.

For Iran, that distortion may now be more dangerous than any foreign adversary.

A recently surfaced video appears to show Mohsen Rezaei, a senior Iranian security official and longtime commander of the Islamic Revolutionary Guard Corps, discussing the idea of kidnapping 1,000 American soldiers and using them as bargaining chips. The video is authentic, but the remarks date from 2015. Their age matters. Yet so does the mindset they reveal.

The more important question is not what Rezaei said a decade ago. It is whether the strategic culture behind...