Russia's Air Strikes on Ukraine

There's a big concern that the escalation will continue. The worst it gets for Putin, the worst it really gets for US security. He could use nuclear weapons in the Ukraine. But more likely, and I think more threatening for the United States, is if he gets into any nuclear exchange with the US. We would be massively damaged. So I think he's most likely to do something like clandestine virus release of human-human transmissible avian flu which is 60% lethal but not directly linked to humans.