I have to rescind any assertion that it was suitcase nukes he referred to.
He referred to nukes.
And even there, I have to admit that its hard to tell when someone is speculating versus operating from hard data.
If such weapons were in this country under the control of a terrorist group they would have been used by now. And after numerous threats we have seen the capacity of these groups for action inside this country decline.
Now I would believe that such groups may have purchased what they believed were the components for such weapons.