The Case for Mosque Surveillance
The vast majority of U.S. mosques presently serves no such role, and their members would utterly reject radicalism, extremism, or violence. Even where there is an extremist presence, that would be absolutely contrary to the wishes of the mainstream in the congregation. The main thing the imams in those places want is to have the police help them kick out the extremists, and not to be too gentle doing so.
But any terrorist Islamist presence in the U.S., present or future, does and will use mosques in this way. If you do not maintain such mosques under surveillance—and particular “certain mosques” already leaning in radical Salafist directions—you might as well abandon any and all pretense of trying to limit or suppress terrorism on U.S. soil.
“Surveillance” in this instance emphatically means human intelligence within the mosque. That means recruiting informants within it, and trying to bring radicals over to your own side, to see what extremists are going to do before they do it. Just how and where is radicalization being undertaken? Who are the key militants? Are there weapons present? What are the overseas connections? And if that means recruiting and controlling imams and religious teachers, all the better.
These tactics are absolutely fundamental to European counter-terrorism approaches, and nobody has the slightest doubt of that fact. That fact is public knowledge, and effectively beyond political criticism. If U.S. agencies claim that they are not doing the same things right now, in American mosques, they are simply deluding the public. They will worry about the freedom of religion lawsuits later.
So, God help me on this, in this instance, Trump is right. The only thing he is doing wrong is talking about it publicly.