Nothing has actually changed except the American mood. Using ground troops in Syria and Iraq is no better or worse an idea after San Bernardino that it was before. The downsides are the same and at this point should be obvious. Lives will be lost, and some of them will be ours. American soldiers can't fix what ails the Middle East. Sure, they can overthrow dictators. They can kill terrorists and push them out of territory. But eliminating the appeal of a fascistic ideology is something else entirely. Replacing a totalitarian regime with some kind of functioning democracy in lands riven by ancient sectarian hatreds and hobbled by political and religious extremism is something else entirely.

Most Americans Now Support Using Ground Troops" (14 December 2015)