282RA and others suggest there is not really a serious Jihadist threat.
Who knows, but consider the British experience.
We have one gang awaiting trial for plotting to bring down transatlantic flghts with liquids, and another who tried to buy surface to air missiles.
Another gang is on trial for an attempted mutiple suicide bombing on our subway system (the detonators fired but mercifully the home made explosive failed).
We have just convicted another gang who had stored half a ton of fertiliser for mixing in to explosive.They were recorded discussing targets.

Would the Dix plot have succeeded?
Again,who knows?
This stuff from 6abc suggests that it had every chance.

"But there are numerous portions of the fort, including areas where soldiers train and gather for maneuvers, that are not protected by any barriers.

Main Street, the primary road through neighboring Cookstown, continues as a public road along the edge of the fort, accessible to anyone, and is regularly traveled by private cars and trucks.

On Tuesday, hours after the arrests and the plot were made public, at least two of the areas directly off the road were populated by dozens of soldiers conducting training exercises not more than 50 yards off the main road.

On Wednesday morning, a dozen soldiers ate breakfast under a wooden canopy in an area of the fort known as Bastogne Range, about 30 yards from a road that carries civilian traffic."