You're absolutely right, and present a workable scenario. They don't need ICBM missiles. Most shipping containers are not checked, only a tiny fraction are inspected. They could ship a nuke, and agents here would arm it. They could slip over the border from Mexico, and have a bomb ready to go in a warehouse in our cities. 12 million illegals easily got here, you think professional spies can't? If NK blows a nuke here, we won't easily be able to pin it on them until they take credit for it. I also say take them seriously.
Agents?? Try Nancy Pelosi. That’s the level of treason in place.