re: The ?surprises? - dirty bomb rockets
Any kind of nuclear research program generates large amounts of low-level radioactive wastes. Loading these up and delivering them with artillery, even if they were a minimal health risk, would cause panic and precipitate massive expensive decontamination efforts. But it would be bad publicity for the terrorists, and very risky politically for their sponsors. OTOH, I wouldn't rule out chemical agents, they would be harder to trace to their source and are readily available.