Mosul
By Very briefly on this nonsense…
The argument that the United States could have prevented the collapse of Iraqi control over Mosul and other areas is predicated on the belief that a relatively small (certainly no larger than 10000) contingent of US troops, supported by US air forces, could either defeat rebel groups or sufficiently stiffen the Iraqi Army such that it could defeat those groups. There is no evidence that this is the case, however; prior to the Surge, much larger US forces were unable to maintain order in Iraq.
This is to say nothing of the fact that leaving a larger contingent was virtually impossible given political reality in both Iraq and the United States in 2011. The “Maliki would have fought for a larger force” is pure hand-waving, and the idea of leaving even 2000 was deeply unpopular in the US. Moreover, had we left a larger force (at any plausible level, which is to say much lower than 130000), it would require significant reinforcement in order to handle problems like this, which would itself prove politically unpalatable in both countries.
Long story short, the central takeaway of the WSJ piece is the effort to pass off the continued disaster of Iraq to Barack Obama, one of the only people in US politics who bears virtually no responsibility for the disaster in Iraq.