North Korea began a biological weapons program in the 1960s and is believed to be able to produce smallpox, anthrax, tularemia, and a number of other pathogens suitable for bioweapons. These may already be on missiles aimed at South Korea and Japan.

Worse, North Korean intelligence agents may have them, ready to strike in the U.S. North Korea’s intelligence agency has a long history of operating in free countries. Their assassination of ruler Kim Jong-un’s half brother in a Malaysian airport could have as easily used smallpox. That attack may have been meant to send two messages to us: they are willing to use nerve gas, and they can deliver chemical or biological weapons in foreign countries.

If genetically modified vaccine resistant smallpox suddenly appears in a few US cities, we will probably have a catastrophe on our hands. We also may not know who is at fault, reducing the value of our deterrents.

The US has spent tens of billions to prepare for a biological attack, but the advantage is strongly to the attacker. The threat is real, the consequences unpredictable, and prevention is difficult.