The pattern to discern from articles like this is that they highlight the threat and not the difficulty of actually realizing the threat.
When you put two layers of improvisation into a weapon the odds of it working are very low. Building an effective homemade grenade is difficult. Delivering it with a noisy machine that limits the size of the grenade multiplies the odds of making a spectacular but ineffective attempt that will only get you noticed.
But it does increase the odds that some consultant will get hired by DHS to write an unreadable report about this supposed threat.
When you put two layers of improvisation into a weapon the odds of it working are very low. Building an effective homemade grenade is difficult. Delivering it with a noisy machine that limits the size of the grenade multiplies the odds of making a spectacular but ineffective attempt that will only get you noticed.
But it does increase the odds that some consultant will get hired by DHS to write an unreadable report about this supposed threat.