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BERLIN — American and Iranian leaders have signaled that they’re prepared to talk. That’s good. But getting results may prove to be more difficult than they imagine.

To begin with, it is most unlikely that any talks could start before Iran’s presidential elections, set for June 12 .

The incumbent, Mahmoud Ahmadinejad, probably fears that just entering into negotiations with the “Great Satan” could alienate some of his core supporters. And an unsuccessful first round would give his challengers political ammunition.

The fact is that the first round is unlikely to be successful. The positions and expectations on both sides, and their notion of who should take the first step, are too far apart.

A senior Iranian...