Despite the odd angle used throughout all the western media propaganda. It was an Iraqi group not Iranian group. The constant push to frame this as "USA vs. Iran" by calling it an Iran-backed group, instead of an Iraqi group, or be specific and state that it was "Islamic Resistance in Iraq" is just befuddling. It's like if the media was covering the current crisis in Palestine/Israel, while never mentioning Israel and instead writing headlines like "USA-backed group bombs hospital in Gaza".
As for why this Iraqi group is able to attack USA, it's likely much more to do with the 13 year old failed US Invasion of Iraq than anything to do with Iran. But It feels like USA is embarrassed enough about that whole thing that they have decided to just ignore that Iraq exists and instead consider this to be an attack all along the Jordan-Iran border, which for anyone geographically interested is just as long as the border between USA and France.
The attacks are attributed to Iran because the Iraqi militias that launched them are IRGC assets, in the same way that no security agency anywhere in the western would refer to Hezbollah as "a Lebanese militia". The chatter in mideast analyst Twitter (representative sample: Rasha Al Aqeedi, Oz Katerji, Nadwa Dawsari) mostly seems to be people dunking on Iran for trying to claim it wasn't behind the attack.
The sense I get is that this is looked at somewhat as Avon Barksdale had given all his crews orders to shoot any members of the Stansfield Organization on sight, and, after a bunch of bloody shootings, tried to claim "oh, I didn't order any of those attacks specifically". That argument wouldn't hold up in court, where the standard of evidence is relatively high; it definitely doesn't stand up in the court of USCENTCOM, where the standard of evidence is probably mostly vibes.
This is normal for US foreign policy thinking. No official enemy has any agency except a few top-tier foreign adversaries, who are all madmen trying to take over the world. If anyone has a grievance with the US it's because Iran or Russia or China told them to because we're so great what else could the reason be? We literally had Nancy Pelosi claiming that people who call for a ceasefire in Gaza are puppets of Putin.
I find it very odd that Americans seem to not be able to understand how a highly nationalist people may object to them staying past their welcome date and seek to attack them on their own accord, and that most of these groups existed well before acquiring Iranian funding.
Most Iraqis still remember tragedies like the Mahmudiyah massacre. The government of the time took them into account and promised to have American bases closed, but reneged. I think you can see how events like that being rampant might drive people to fight, even a generation later.
In large part she was probably not wrong given that a lot of calls for ceasefire and in support of genocide of Jews come indeed from Russian troll accounts.
As for why this Iraqi group is able to attack USA, it's likely much more to do with the 13 year old failed US Invasion of Iraq than anything to do with Iran. But It feels like USA is embarrassed enough about that whole thing that they have decided to just ignore that Iraq exists and instead consider this to be an attack all along the Jordan-Iran border, which for anyone geographically interested is just as long as the border between USA and France.