The gear and training the US had let a force severely outnumbered, with little to no combat experience, use strategic planning and tactical oversight to completely dominate and ass fuck a military force that was fighting on its home turf, that was dug in with prepared emplacements and fixed positions. After 40 days and 40 nights of bombing, like it was the Bible or some shit, the ground forces utterly destroyed Saddam's army in less than 100 hours after lunging out of Saudi Arabia, into Southern Iraq, with the second prong driving into Kuwait, then turning and pushing the retreating Iraqi Army into Iraq and destroying them despite the fighting retreat.
That was 27 years ago. With gear two or three generations ago. With training that was largely untested (Aside from Panama, Grenada, and Nicaragua, which were short, limited engagements) outside of theory and constant practice that in a lot of way is predicated and not applicable unless we're going against another huge military force. Now we've got new gear, better gear, leadership with combat and theater experience, we've had a couple years to rearm, to retrain, to buff back up force level numbers, to shake the careerists out from the Join4GIBill guys, to attract a new generation of lower enlisted and officers, to build up stockpiles of vehicle parts, vehicles, and munitions. To work out the worst of the bugs in the new systems.
The US military excels at fucking up other armies. The doctrine specifies key points to control.
Iran is thinking that their hardware, which is either all make believe or old shitty Sov-Tech or Sov-Tech knockoffs, is a match for what the US military fields, when, in fact, the US Army might as well be invading aliens.
Iran needs to stop and realize that the US will be able to come at them from Iraq, Afghanistan, and Turkey, and that's not even counting the fact that every Marine still living will be furiously masturbating with a crayon in each nostril at the thought of a mass amphibious warfare landing, preferably a grueling one that requires each fucking inch fought for, because that what Marines secretly fantasize about while chewing on the box of crayons they found under the table.
The pretty much "accepted fact" since World War Two are the words of a Japanese Admiral (or General, I can't remember exactly) which was "If you can't defeat the US in six months, you have lost the war". But the Middle East and a lot of other small countries don't get that. Most of them can't grasp just how BIG the US is. Hell, there's people from Europe, hell, people from the US, that don't understand just how massive the US actually is both in land and population. Most people don't grasp just what kind of industrial potential the US has if they were ever to go back on full war-time footing ala WW2. Russia and China both get it, because they are massive countries with the same advantages and potentials as the US. Europe kind of gets it because they're industrialized modern Western nations, but a lot of Europeans I've met don't really seem to grasp it. Hell, most AMERICANS don't get it.
Even during the War on Terror, a global effort, we didn't really go on war-time footing. The ship building and refit schedule stayed roughly the same (IIRC our hull numbers actually went down), the maximum amount of military troops didn't go up extremely (IIRC it was only like 30K more troops), hell, even ammunition and other munition production didn't really go up (Remember how law enforcement and civilian acquisition of ammunition went through shortages because Remington and Winchester didn't want to run the financial risk of opening up another factory), and even vehicle replacements didn't see massive production lines. No real pushes for War Bonds, no Victory Gardens, nothing like that.
Most of America went along business as usual. We're that fucking big that for the majority of Americans, the GWoT might as well not have been going on.
One thing weird about the Middle East, is they absolutely forget what happened only a few months or years ago. Saddam knew good and damn well he'd get his shit pushed AGAIN if he didn't let the UN inspectors into his country with full access, but instead he refused and baited Bush and then ended up hiding in a dirt hole before they hung him. He'd just watched the US military ass fuck Afghanistan, who had held off the Soviet Union for years, in less than 30 days. Watched the same build-up as happened in 1991 on his borders, and STILL thought this time would be different.
They threaten the "Mother of All Battles/Wars" and think that'll push us back. But they've forgotten something that Western Nations still flinch at. We had our "Mother of All Wars" twice. Once we used chemical weapons and lost an entire generation in muddy trenches. The other one ended with the flash of nuclear weapons, Russians raping most of Eastern Europe, and the US killing anything that moved. Their "Mother Of All Wars" has been what the Western Powers consider "Brushfire Wars" and "Police Actions", with limited air power, almost no naval power, short supply lines, and human wave attacks that the West had to give up in 1919. Their military doctrine is largely KEKEKEKEKEKE zerg-rush, random ALOHA SNACKBAR, and/or "WE MUST PROTECT THIS HOUSE!" shit. Ask anyone who has ever had to try to teach military tactics to anyone from the Middle East what it's like trying to teach them modern tactics. Modern tactics might as well be witchcraft to them, partly because of how their society and culture is set up dictates how their military is set up which is prohibitive toward modern military force and the internal military culture.
The Iranian leadership HAS to know that the massive juggernaut that is the US military can stomp a mud-hole in their shitty little country with a kill rate of like a 100:1, but they also have to appear strong to their neighbors and their population after decades of burning the American flag, screaming Death to America, and threatening the US, banking terrorists, and sending in foreign fighters and equipment into Iraq.
It's the game they've been playing since after the CIA fucked up their government, and it's played pretty well, since aside from a few cruise missiles, the stench of Vietnam kept the US from getting into foreign wars for decades. Panama and the Gulf War were kind of looked at by the American electorate as one-offs and "let's not push our luck" until 9-11 happened and it showed that while the US sucks at occupations and nation building, we can ass stomp another nation's military into the fucking dirt like it's Weasel Stomping Day.
There's no specter of international Communism over the world, the US and the USSR aren't trying to divide up the world by idealogy. There's been a profound shift in global thinking where the threat is looked at more along radical Islam instead. Even Russia and China hate radical Islam, and suddenly, thanks to the European Migrant Crisis perception and terrorist attacks, more and more of the big-boys are aware of just how much more dangerous it is to have a nation that follows extreme Islam than the idea of the US getting a few bases in the area, and hell, the US might agree to split the country ala Europe circa 1950's in return for assistance.
And the Middle East has been pumping oil since the 1970's while the major players (China, Russia, the US) have largely sat on their stocks (In the USSR's case it was a problem of financing new drilling, a problem they don't have now) while letting the Middle East deplete their stocks. In some ways, the Middle East acts like the oil will never stop (Even though slant drilling into Kuwait is part of why the 1991 Gulf War happened) because it's been flowing for two generations.
And then you take all of that, and you add in a wild card that nobody really knows how to handle.
Trump.
He's either a complete idiot who's borderline illiterate and can't tie his own shoes who is a racist, bigot, homophobe who drools non-stop and makes DURRRR noises when he breathes or he's a 4D Chess Mastermind dancing everyone else to his hyperspace phasic fiddle tune.
Either way, he's not the normal slick politician who respects and knows the way the international politics game is played. He has no political background, so you can't look at his stance on various policies. You have to go TWITTER to get an idea of what he thinks of various policies.
His Sec-Def is a guy named Mad-Dog who apparently spends most of his time keeping Trump from physically launching himself in an ICBM at people who insult him over Twitter.
No matter what he does the Western Media paints him as a blithering incompetent who is going to plunge the world into war. That self-same media makes it seem like the US is on the edge of civil war or mass rioting any day.
But, the world had 8 years of America Apologized to the World Tour, including kissing Iran's ass along with literal fat stacks of cash being delivered by plane. Red lines drawn in the sand that were jumped over before the line was finished being drawn. Iran capturing ships and getting ass kissing apologies. ISIS running rampant everywhere.
BUT, Trump didn't invade Syria, instead he sent in Special Forces and launched a shit-load of 20 year old missiles at Syria, but Assad is still in power, which might have the Iranian leadership figuring he's just going to shit-talk them on Twitter and maybe they can get him to send them a couple of pallets of cash again.
But things in America are weird right now. The Dems are acting like it's 1950's and they're the Republican party, calling for war against Russia, calling for McCarthism, and all that good stuff. Politically, we're a little unstable because Trump getting elected seemed to have given everyone a stroke. Boomers are dying off, losing power, and Gen-X, who grew up seeing airlines explode on the news and hearing about how Iranian backed terrorists hijacked something new this week or blew something up, is coming into power and nobody is sure how Gen-X is going to actually react to shit. Gen-X grew up on Rambo, Aliens, Predator, and have a massive does of "Fuck you, sand-nigger, we're fucking America!" while being lectured at by a bunch of dirty hippies about how war was evil until it was time for them to go to war. Something like half of the House & Senate are on medication for fucking Alzhiemers and dementia, or have diseases that cause mental problems (ahem, McCaine), so they aren't exactly stable. We've got a Chief Justice who sleeps through shit, Intelligence Agencies we've read proof are a bunch of speds, and everything is all confused.
So Iran may be thinking that we won't do shit and they can just keep going like it's the status quo of the last 4 decades because of too many internal problems here in the US and that the people that worked on the Iran Deal will keep Trump in check.
Or they've made backroom deals like Hillary was still in power and think the people they've donated to and given money to can stop Trump.
Or maybe they've finally bought into their own rhetoric and believe they can honestly take on the US military, defeat the US Navy, and seize control of Gulf waterway access.
Even though every time the Arab states have tried to take on the US in an actual military conflict, they've gotten butt-fucked till their eyes bugged out, but every time another country starts down the Highway to Rough Anal Sex, they think that this time it'll be different.
"IT WILL BE THE MOTHER OF ALL WARS!"
It's like they never fucking learn.