alt Hacker NewsDelivery of nuclear weapon via shipping container might seem like a deterrent but it's kind of the opposite thing.
For something to be a deterrent it must have a few properties. Delivery taking a non-zero amount of time and producing a gigantic visible ordeal from outer space is a feature here. A container bomb going off somewhere in a civilian logistics chain is a surprise. Surprises cannot be deterrent by their very definition. The inability to ~instantly attribute the attack to some party would only invite additional instability.
The deterrence aspect is having nukes your adversary can't be certain of getting rid of on a preemptive strike.
You don't have to have them on a container ship. You need the credible threat of being able to do so.