Between 2005 and 2014 the US military gave the Iraqi army 14 billion dollars worth of equipment. Much of that has fallen into ISIS hands because the Iraqi army are renowned for being absolute
****, downing tools and legging it at the first sign of trouble.
The US recently wanted Japan to explain why ISIS are rolling around in relatively new Toyota pickups, despite the fact they're also rolling around in M1A1 tanks, Humvees and using millions of dollars worth of US equipment.
America's solution to the problem of ISIS getting all that hardware left by the fleeing Iraqi army? Send the Iraqi army 150+ new M1A1 tanks, 55k rounds of anti tank ammunition, 600 million dollars worth of artillery hardware, 700 million dollars worth of missile hardware and 2k AT-4 rockets.
Like a large part of that won't go missing too.
And why do they do it? To keep American's in jobs. The US has been manufacturing tanks continually since the end of WW2. The war economy got them out of the depression era and they've just been churning out tools of war since.
Despite the fact that for the last 15+ years the US military has been telling congress to stop buying equipment it doesn't need.