Here's Jonathan Tepperman in an excerpt from a recent World Affairs podcast:
I don't think terrorism is an existential threat [to the United States] ...because the number of Americans killed every year in terrorist attacks is vanishingly small. More Americans are hit by lightning every year than die in terrorist attacks. More Americans drown in their bathtubs every year than die in terrorist attacks. The number of Americans killed by terrorism since September 11th, 2001 is something like 100 or 150. It's minuscule. And that's compared to more than 40,000 Americans who have been killed in handgun incidents. And double or triple that figure who've been killed in car accidents. The existential threat, if it's there, comes in overreacting, in responding the wrong way to terrorism but not in the terrorism itself.
And then there are a lot of scary trends in the world. There are a lot of countries that are behaving in scary manners today. None of these represent existential threats to the United States either. Not China. Not Russia. For the simple reason that The United States is so overwhelmingly preponderant today in terms of wealth, innovation, and in its military power, that none of these countries can offer real competition.
Now climate change. There's a real existential threat that defines the idea of an existential threat. And political dysfunction. Gridlock. The failure of our legislative branch to legislate. That potentially represents an existential threat because until that is resolved in some fashion none of these other problems can be addressed.