Why do you think the number of people in Iran matters?
I think most of what you said is just speculation, not founded on reality. The only thing that would stop the US from invading Iran in under 3 months is political will.
Russia doesn't have the scale and power of the US airforce, or the ability to project that power using the US navy and all the bases in the middle-east. Any comparison with russia at all makes me question your entire analysis.
Iran is big and geographically challenging, Afghanistan is notorious in the same sense as well, even more so by their infamous defeat and expelling of Russia in the 80's. The US invaded afghanistan in a matter of 1-2 months and held on to the country for 20 years.
Establishing a FOB initially will be challenging but with Kuwait and KSA eagerly cooperating, it won't be a challenge.
Drones are effective when your enemy is nearby and you can project it against them. Iran can threaten just about any US interest in the region but not the US homeland itself. They can't attack Europe because that would risk drawing them into the conflict, so their only option is to attack existing enemies in the region and do their best to inflate the price of oil.
And therein is their strategy that might win the war, it isn't all the reasons you listed, but political will as a result of economic pressure. The US lost in Afghanistan, Vietnam, and even arguably in Iraq because of loss of political will to continue the conflict. But then again, the current administration will not be deterred by pesky things such as the will of the american people, they'll use it to declare emergencies and attempt to hold on to power instead. The only thing that can defeat the US right now is the republican party in the US willing to turn on their beloved dictator.
> Ukraine has people making them in basements. Presumably, so does Iran.
The US has bunker-busters.
Even though your analysis is full of many technical flaws the most critical flaw in my opinion is how you aren't considering aerial advantage for the US, but yet you seem to think drones are an advantage. Drones are only useful at attacking pre-determined regional targets to influence political will. For the US however, unlike Russia, the US doesn't have a decrepit airforce, and doesn't flinch at launching $70~M/launch tomahawks. The ukrainain army right now isn't withstanding a constant barrage of bomber jets dropping on them. Russia is several decades behind US equivalent fleets from what I understand.
The US military hasn't been sitting on their hands watching the Russia-Ukraine conflict either. They've been testing all kinds of anti-drone tech in the desert for a while now, but this is the real opportunity for them to battle-test different techniques. No one is sanctioning the US either (more like sanctioning itself), and there is no real or practical shortage of war-chest funds (unlike Russia), and having a big war every two decades means the US military-industrial complex far more capable to meet the supply-chain logistics demands.
The US military certainly is the biggest in the world, dwarfing all other countries' militaries combined. But the thing most people don't realize is that is not what makes it the most capable invading force in the world, it is the sheer efficiency of the logistical effectiveness unseen the history of war before, backed by the ability to fund years-long wars without so much as flinching on the domestic economy front.
I would argue that the if the political will existed, the US can invade the entire region, from the Mediterranean to the Himalayas in less time than how long Russia has been at war with Ukraine. Even if the US couldn't use the bases and airspace in Europe at all, the calculus remains the same.
> This worked a lot better when the trouble spots couldn't do much to them.
Huh? what do you mean? They're entirely designed to address hostilities, they're not designed establish access in a non-hostile littoral, this goes back to WW2 beachead establishments (like normandy). The carrier ships are never meant to be close to land to where they're a target, but the carrier group itself is entirely designed to establish a beachead and deploy an expeditionary force under hostile conditions. I admit, maybe my history recall is lacking, do you know of any post-WW2 conflicts where the US navy established a beach head as part of an invading force that didn't face both aerial and naval resistance? Iran and Afghanistan didn't require it, neither did Korea or Vietnam as far as I know.