Expanding on my post #9. Stalin was a bad man, an evil man. Should FDR have invaded Russia while at the same time fighting Hitler and Tojo? Of course not.
The same applies in regards to Bush II. He had his hands full in Afghanistan. Yet Bush II decided to open up another front. Not only did that divide our resources, it angered many folks who would have otherwise stayed on the sidelines.
The AQ terrorists we were fighting in Afghanistan for the most part fled to Iran and Iraq long before we invaded Iraq.
They returned en masse to Afghanistan in Obama’ term when Obama’s VP Biden declared that the Taliban were not an enemy... and the Obama admin took the pressure off and began supporting them setting up a Taliban office in Qatar as part of their idiotic - and premature-”reconciliation efforts.”