Here are some population pyramids for Iran I’ve just found here:
You don’t go to war when your birthrate has collapsed. Families with five sons might not grumble too much when one of them gets his head shot off in a war with Saddam Hussein c.1984. Families with one son will bribe or riot when the politicians start talking holy war.
Behind their bluster, or behind the wall of neocon propaganda, the Iranians are eager for a deal. It’s the same with the Chinese. It’s the same with the Russians.
About the only militarily important countries in the world not facing a demographic crisis are – er – Britain and the united States. Which countries have been most often to war in recent years?