Far too many people think Iran would be a pushover like Iraq in the two wars we had with Saddam. They share a common border and a common religion sect controlling the current governments. Both are large oil producers but Iran has other businesses.
The difference between the two is stability. Iraq has little stability and Iran may have problems with their elected people but not with their religious elite. When we invaded Iraq, Saddam was a maniacal, paranoid Sunni leader who had kept control of the 66% of the country who were Shia.
In 1980 Saddam attacked Iran with our help. The war lasted 8 years costing his military several thousand troops. Iran lost about a million people. Saddam sued for peace after the last battle where his dug-in army ran out of artillery, mortar shells and ammunition after human waves by kids walking through the minefields. Behind the kids were militias followed by regular army, followed by elite guards units. They mowed them down and blew them apart but they kept coming. That is what their religion requires them to do to reach heaven.
Iran is 94% Shia and 5 % Sunni and does not have the weak military Saddam attacked. Iran has advanced high-speed silkworm missiles which might be able to overwhelm our Navy in the little Persian Gulf. They have purchased and upgraded their advanced air defense system with modern anti-aircraft guns and missiles.
Iran has 83 million people in the country and tens of thousands outside the country willing to die to defend their religious leader and country. Thanks to Trump’s bullying and prodding, few if any country will join us because they see him starting the conflict. If we are kicked out of Iraq, we lose a land base and Iran may gain additional supplies, financing, and troops.
Iran will not be a pushover or a short war.