The Washington Post has a sad but revealing story of how Iraqi forces lost the key city of Mosul more than a year ago. Reporter Loveday Morris obtained a copy of an Iraqi parliamentary report still kept secret.
The lede: "The top Iraqi army officer for Mosul remained on vacation last summer
despite repeated warnings that Islamic State militants were planning to
seize the city, and his units had less than a third of the soldiers they
were supposed to have on the day of the battle."
The story confirms what I had heard from Americans with extensive contact with Iraqis after the U.S. troop withdrawal. The best American-trained officers were replaced by men loyal to Prime Minister Maliki, training atrophied, and corruption grew.
While in theory a U.S. troop presence might have made these developments known and reversible, the fact is that the Iraqi leadership wanted the Americans out, so the Iraqis insisted on compliance with the Bush-signed withdrawal agreement.