In short, Iran-backed forces seem to associate the alleged attack by Israel with our allowing this.
Perhaps if some reports have said Russia and Iranian-backed forces have clashed in Syria, it's a similar scenario.
Iran-Backed Forces Blame US for Attacks on Bases in Iraq
By Associated Press, Wire Service Content Aug. 21, 2019, at 11:16 a.m. More
4-6 minutes
By QASSIM ABDUL-ZAHRA, Associated Press
BAGHDAD (AP) — Iraqi paramilitary forces backed by Iran said Wednesday they hold the United States ultimately responsible for a series of attacks targeting their bases in the country, pledging to defend themselves against any future attack.
The rare statement issued by the state-sanctioned militias known collectively as the Popular Mobilization Forces, or PMF, said the group has accurate information that shows the U.S. brought in four Israeli drones this year to work as part of the U.S. fleet in Iraq and target militia positions in Iraq.
"We announce that the United States is ultimately responsible for what happened and we will hold it responsible for what will happen as of today. We have no choice but to defend ourselves and our bases with the weapons at our disposal," said the statement, which was signed by Abu Mahdi al-Muhandis, the deputy head of the PMF.
https://www.usnews.com/news/world/articles/2019-08-21/iran-backed-forces-blame-us-for-attacks-on-bases-in-iraq