I vigorously rejected that type of reasoning by the anti-war side who made the same charge in regard to how many Iraqi insurgents and terrorists we fought there.
And I rejected the charge for Afghanistan, for that matter.
Enemies replace losses, I said. And the enemy in the Iraq War did just that until the real metrics of success moved in our favor and then our enemies lost heart and could not replace losses. By the time we left Iraq, there weren't many jihadis left.
As I pointed out at the time, if the enemy replacement effort was proof we were losing the Iraq War, why wasn't our similar effort to replace losses and keep our force levels up (and even increase them eventually) not proof that the enemy was losing?
So no, the constant level of the enemy in ISIL-held territory isn't proof of our failure.
Not that I have no criticism of the war. It is painfully and unnecessarily slow, I believe, and gives our enemy time to inflict more suffering--whether in the Middle East or France or America.
But the ongoing air attacks and more recent commando raids could have an effect in shaping the battlefield much as the years-long jihadi effort against Mosul prior to summer 2014 set up the Iraqi security forces in the north to collapse when hit hard.
I do suspect that when we finally move on Mosul, we could see a jihadi collapse in Iraq.
UPDATE: More from Strategypage on the need for success to maintain ISIL:
This interference has become a growing problem for Islamic terrorist organizations. That’s because the continued use of international media to keep people (largely disaffected Moslems and Western leftists looking for a new lost cause) informed about how the terrorist group is still around was being diminished by this interference. Maintaining such visibility is essential for recruiting. Al Qaeda has always recruited from the least educated and most desperate Moslem men out there and ISIL (Islamic State in Iraq and the Levant) continued that custom. Religious fervor was not crucial but the willingness to suffer and die was. These recruits are attracted to the image of al Qaeda as being constantly active, no matter what damage they suffer. Also important was maintaining support from older, more affluent, and less desperate supporters.
ISIL needs the image of the strong horse. We must deny them that image by openly beating them in Iraq. Again.
Oh, and the "this interference" reference is about anti-jihadi messages on social media that enrage the true believers to the point that they reveal secrets; and--when they come from government posters--scare off the merely agitated.
So despite deserved mockery of hashtag campaigns, the State Department work in this area on Twitter isn't a waste of time. So good job, guys (and gals)!
Do read it all. I have a variety of information sources that I roll through every day, but if you don't want to bother reading The Dignified Rant, I'd choose Strategypage as the one source to read.