ISIS does not represent an existential threat to the United States. Not even close.

Let me tell you about an actual existential threat that America once faced. It starts with the Soviet armament called the R-36M, the largest ballistic missile ever built. Still in service, the R-36M can be equipped with as many as 10 strategic nuclear warheads on separate entry vehicles, each with a yield of between 500 kilotons and 1.5 megatons of TNT, or a single ultrapowerful warhead with a yield of up to 25 megatons.

The nuclear bomb that obliterated Hiroshima, killing roughly 75,000 people instantly and tens of thousands more later, was a mere 16 kilotons. A 25-megaton warhead is more than 1,500 times more powerful. If dropped on downtown New York, such a weapon would annihilate most of the city, lay waste to the suburbs, and cause thermal-radiation burns from Stamford, Connecticut, to halfway across New Jersey. Millions, possibly tens of millions, would be killed.

During the Cold War, many R-36Ms, and thousands of similar, only somewhat less terrifying weapons, were pointed at American cities and ready for immediate deployment by the Russians. It was without question an existential threat to the nation (and the Soviets, too). If the right people pushed the wrong buttons, hundreds of millions of Americans would have been vaporized in minutes. It would most likely be the end of the country, and maybe even the whole of humanity. We came very close to the end on multiple occasions, most of them false alarms.

Mass death by nuclear fire is a true existential threat. ISIS isn't.

But you wouldn't know it listening to the Chicken Little caucus in Congress, not to mention the media soiling themselves en masse over ISIS. Look, this Islamist extremist group is nasty and violent and dangerous. But it is also a threat roughly one billionth as formidable as the USSR was. Scott Brown, GOP candidate for Senate in New Hampshire, says in an advertisement that "radical Islamic terrorists are threatening to cause the collapse of our country." Sen. Dianne Feinstein (D-Calif.) went further, writing that "the threat from ISIS cannot be overstated." Mainstream news has been grossly hyping the threat as well — the ISIS beheadings are the most widely reported event of any kind since 2009.

These lawmakers and journalists are acting like unpatriotic, irresponsible cowards. A moment's considered thought reveals that ISIS is a tiny, manageable threat. Stoking panic by breathless, hysterical exaggeration, especially for possible momentary political advantage, is despicable.

I've been writing about how we need to be realistic about our nation's capabilities; how we just can't micromanage the internal politics of nations in the midst of civil war. But we also desperately need to be realistic about terrorism. Our new dumb war in Syria, like the one in Iraq before it, is driven at root by a frankly laughable fear that America itself is at risk of serious attack or even destruction.

The Soviet Union was a massive industrialized state with cutting-edge science and technology. ISIS is a few thousand men with a messianic complex driving around in pickup trucks. They have a lot of light arms, suicide vests, and a bit of armor and artillery, most of which they picked up off the ground. They are by all accounts brutal and monstrous, but they simply do not have the capability to seriously harm the nation.

ISIS may well try to launch an attack against the United States. The 9/11 attacks did do great harm (though even that was not even close to existential damage). But covert terror attacks are pretty easy to disrupt with even half-decent intelligence and police work. And to the extent that ISIS tries to evolve into a normal state and frontally attack mano a mano, it will become easier, not more difficult, to defeat them. Think of an ISIS navy trying to take on the U.S. Fifth Fleet — the very idea is ludicrous.

The actual greatest danger facing America is overreaction: letting ourselves get dragged into another doomed ground war. The Iraq War did at least an order of magnitude more damage to the country than 9/11 did. It may be the case, as Josh Marshall argues, that the ISIS beheadings were such effective propaganda that we're simply trapped right back in the Bush-era terror politics, where the best fearmonger wins. The only losers will be American troops, who are every day more likely to be dropped into another pointless, unwinnable war; the American people who will have to pay for it; and the civilians killed by accident (note we just loosened collateral damage standards on airstrikes).

But those with sense can see that we have an obligation to at least try to prevent disaster. So don't panic, folks. America is strong. The fact that we managed a decades-long standoff with a nuclear superpower is proof enough of that. Other nations have survived worse — during World War II, U.S. firebombs and nukes reduced practically every Japanese city of any significance to rubble, and Japan survived. ISIS is little more than a mosquito by comparison. We'll be fine.