The troop withdrawal created a ton of surplus armament. Through the so-called “1033 program,” police departments can acquire excess military gear from the Pentagon for free.
Source: https://www.stephensemler.com/p/how-the-iraq-war-turbocharged-police
I was deployed to Iraq in 2010, the mission at that time was changed and called “Operation New Dawn” this was Obama’s drawdown of forces. The base I was on had one more deployment after us then it was turned over to Iraqi forces and we pulled out, mostly.