This has been well discussed in at least 3 to 4 other threads so far.
And I agree that if they could have used them, it would have already happened. Fortunatly for us these nukes require periodic maintenance from qualified technicians with the proper parts and equipment. the best the enemy could hope for a some dirty bombs at best!
And that's just in the last day.
These stories have floated around since before the end of the Cold War. They were supposed to be brought in as a deterrent to an attack by the United States. The FBI took the story serious enough to scan the cities with geiger counters. The problem lies in being able to shield the bearer of the bomb from radiation in such a light package. It all sounds far-fetched but a former intelligence official wrote the book.