Could Iran repel the US invasion?
A ground invasion would be an incredibly expensive operation, both in terms of dollars and lives.
Everyone remembers the last major US invasion – Iraq. It looked so easy.
Take a look at this map though:
First off, where will you be attacking from? Iraq is not likely to be very happy about being a staging area…its relations with Iran have improved a great deal since the fall of Saddam.
Turkey is certainly not likely to welcome a US invasion force at this point in time, given the current rather tense relations between the countries.
Pakistan won’t go to war with Iran on the behalf of the US, nor will Afghanistan.
That leaves only an amphibious assault. Not a very attractive idea.
Next up, you will notice that Iran is basically surrounded by mountain ranges. Wherever you want to invade from, it’s going to be very different than Iraq or Syria. There will be no easy terrain to roll your tanks through.
Air supremacy will be an issue. While the Iranian Air Force will be no match for even a single carrier group, defensively, the S-400 (alongside other AD assets) makes this a tricky proposition.
Russia is very likely to send significant military aid to Iran. There’s no way to stop them from doing that unless you want to attack Russia. So even if you manage to destroy most of the current air defence capabilities, Russians can send replacements.
In the end, it would be very unlikely to complete the invasion of the whole of Iran before either the Congress or the public intervenes.