Uh, a bit late now.
Sorry, the FBI is already telling us that these guys acted alone. When is the US government going to stop pretending that a terrorist attack is not really a terrorist attack unless it is done by external forces sent to America under the direct control of some foreign government or terrorist organization? If muslims resident in the US are being radicalized by foreign activists, either political or religious, then it is just as serious (and perhaps more so) than an external attack. It’s all part of the same jihad.