As we saw in the foiled plot on Germany, these are “hybrid attacks” Usually these terror cells commit one brazen direct attack aimed at distracting forces, before launching another attack. We also don’t know what their target was. There could have been a dignitary on base that day, a high ranking commander transiting through, or specific equipment in transit, that these individuals were trying to target near a perimeter. In which case the chemical explosives they had would have been more than sufficient even if they didn’t make it very far. We need the full picture before we can draw conclusions.