“Who authorized this? “
The US Congress with the AUMF in 2001, right after 911.
It’s a blank check for any POTUS and allows Congress to look the other way, being derelict in their duties.
And, a friggin’ travesty.
If an authorization passed in 2001 authorizes involvement in a war that didn’t even start until 2011, our form of government is in question.
Congress has the power to declare war - previous Congresses don’t have the power to declare that later Congresses don’t get to decide!