Yeah their military strength is really in its rocket/missile capability. They are fairly accurate and the ones they fire from vehicles can fly under US missile defense systems.
From Iran’s perspective, yes they are annoyed the US backed out of the JCPOA and imposed the harshest sanctions its ever imposed on the country. It’s why domestically the reformists in Iran have lost all political capital - the hardliners said that the US would break a deal.
They don’t want to renegotiate the deal that they didn’t break, they want all parties to go back to those terms. The US wants a more thorough and limiting deal that includes rocket/missile restrictions - something the Saudis and Israelis also both want & don’t want to give the guarantee that the next president won’t just scrap the same deal again.
Neither side trusts each other for a split second & I think the diplomacy here will fail, unfortunately. The other parties to the agreement, the EU, UK, Russia and China, can’t really do much to convince either side to change their stance.