history, even in its making, always lacks a control (the experiment kind). We lack a negative control for the current policy, perhaps the current policy is working very well, that in its absence millions have perished in all sorts of timelines we are not in (as a consequence of policy).
One could argue, e.g., that the Obama administrations policy for safeguarding US diplomatic stations oversees "doesn't seem to work" on the grounds of Bengazi. We can draw all sorts of comparisons and depending on our persuasion argue that it does or does not work, but anything resembling saying it does work would have to include that it working will include some failures.
In American terms, on balance, a very very very small minority of fatalities as a consequence of gun violence is a consequence of ISIS policy. If we assume that it is a goal of the US to curb gun violence, one might argue that of all the sources of gun violence US policy is most successful as it pertains to curbing gun violence sourced directly or indirectly from ISIS.
The same likely cannot be said for Europe, particularly France (unless overall gun violence is much higher than I assume).
In France ISIS is a primary killer of people. In the US it barely scratches the surface necessitating the use of several decimal placeholders before one can enter a value.
Certainly e.g. a large ground pretense that pries the land away from ISIS is alternative strategy but I am not inclined to do it simply because it is different and the current strategy "doesn't seem to work".
What is the criteria for it working? If one person a century is killed in the US directly or indirectly by ISIS, would that be success or failure? Or one a decade, or a year, or 7 a century or 9 a day? Certainly San Bernarndino is tragic and bad, as were the Paris Attacks, and it would seem that (particularly in the case of France) that a good argument for failure could be made, but this is a road where one needs to define success (IMO) as it is the lack of defining success (e.g. Viet Nam, Iraq II, etc.) that affords paths that never survive even a casual cost-benefit analysis after the fact.
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