I am seeing a lot of arguments and ideas regarding how to fight ISIS and how to deal with Syrian refugees that have a lot of emotional appeal. But that appeal does not mean that the arguments or ideas will be practical tactically, operationally or strategically.
In fighting ISIS and other terrorist organizations we first must decide who the enemy is. Is the enemy all Muslims or just those who choose to join terrorist groups? If it is the former, we are in serious trouble since Muslims greatly outnumber Americans. If it is the latter, then we must be careful not to alienate Muslims who might be neutral or even willing to ally with those who fight the terrorists. By alienating those who would at worst stay on the sidelines, we will only create more enemies to fight.
Denying entry to all refugees or carpet bombing the middle east have great emotional appeal, but on the battlefield will have little utility. We bombed enemy populations indiscriminately during the Second World War, but post war studies found that such bombing did not negatively impact the morale of those populations, or lead to the defeat of their nations. What won the war was defeating the enemy on the battlefield.
Before you can defeat or destroy the enemy on the battlefield you first have to identify him. In a conventional war this is made easier because the enemy is wearing uniforms and traveling in marked vehicles. On an unconventional battlefield, which is the kind we face now, the enemy is deliberately hiding among the local populations.
In counterinsurgency doctrine, the local population is considered the center of gravity, or the prize to be won away from the insurgents. The goal is to separate the population from the insurgents to protect them.and to persuade them to support the government. You can't do that if you are bombing or attacking indiscriminately.
Counterinsurgency may not be a viable strategy, if only when used by an occupying power, and certainly when that power lacks the commitment to execute that strategy over the long haul -- meaning, over a period of decades. But when it comes to operating on the battlefield against insurgents, counterinsurgency doctrine will be effective where conventional tactics, doctrine and strategy will not be.
Find, fix and kill. That is what we want to do with the enemy. To do that we must separate them from the population. Once we do that, lethal force becomes much more effective.