So they don't admit to it, but they do have soldiers (IRGC) fighting in Syria and Iraq. This has helped them gain valuable experience and battle hardened soldiers.

Also, they know their weaknesses better than any other nation. They fully expect that any invasion of Iran will come from a significantly more powerful nation, so they're practicing asymmetric warfare. Their heavy investments in drone and missile technology, as well as small vehicles that are hard to detect, leads to this conclusion.

Their goal is to make an enemy invasion as painful and chaotic as possible.

Potentially closing the strait of hormuz is a part of that strategy.

Thus, this military exercise.