A CBRN (Chemical, Biological, Radiological, or Nuclear) attack. Yeah, its probably irrational, but its also likelier than you think.
When the Soviet Union fell, all sorts of WMD goodies were on the table, some of them have been misplaced, some of them have been shittily stored. Chemical weapons are a dime a dozen, because nerve gas is really easy to make. Its just bug killer with a few added things. So every tinpot asshole dictator has them.
Bioweapons are the stuff of friggen nightmares for me. If you want any clue how vunerable we are to that, look up Operation Dark Winter. Like I said with the Soviet Union thing earlier, the stuff was and still is out there, and you can work the stuff in your high school chemistry lab. If some asshole used smallpox agaist us (this is Dark Winter in a nutshell) we as a country are screwed, hard. Not global pandemic super diesease, but mass chaos. Add to the fact both the U.S. and the Soviet Union spent billions on weaponizing viruses, making metric shit tons of the stuff (the Soviets produced so much of one agent to give every man, woman, and child on the planet four leathal doses) and the accounting is off... Yeah. No.
Radiological weapons, dirty bombs, scare me a bit less. Those are terror weapons with little damage other than one burst of radiation in a given area. Since I don't live near a major target area (famous last words) I shouldn't have to worry. But still, this is scary.
And while the idea some mideast extremist group could fashion a nuclear weapon and deliver it to the United States is a far fetched one, its still possible. All the physics are out there. And it doesn't help the FSB (Russia's FBI, basically. But they do a lot of stuff close to Russia) supports a nuclear market in Moldova, with ex-KGB colonels looking to sell weapons grade material to be used against America and the West. Tinpot assholes like the Ayatolla of Iran and Kim Jong Un with nukes also scares me, because they're fanatical and willing to use force to acheive their goals. Add this to the Pakistan-India struggle (both also have nukes) and China, and there are a lot of assholes out there, with nuclear weapons, motive, and means to deploy them against the West, with no effective countermeasure, and leaders who would not retaliate. I don't think any of the scenerios above would follow our policy of retaliation (A nuke is a germ is a gas shell is a dirty bomb, and the response to those is a nuke). Its comforting to know some liberal is going to wring their hands and write a strongly worded letter while a bunch of us are dead.
Strangely, though, I'm at peace should the U.S. and Russia decide to launch on each other. Odds of survival after a nuclear war are low, so I pretty much accept that way of going.
But WMDs are scary. It doesn't help I read everything I can about them.
