U.S. defense policy has long made Colorado and its neighbors into an intentional target for nuclear weapons.

If for some reason you’re thinking about nuclear warfare today, here’s an un-fun fact: U.S. defense policy has long made Colorado and its neighbors into a potential target for Russian nuclear weapons.

The “hundreds of nuclear missiles” stored across the Interior West “are not meant to be launched, ever,” as Tom Collina explained for Defense One. Instead, the deployment was meant to force Russia to spend hundreds of its own weapons obliterating the regions’ far-flung silos, Collina argues.

“Their main purpose is to ‘absorb’ a nuclear attack from Russia, acting as a giant ‘nuclear sponge,'” he wrote. And the nation’s new secretary of defense has made much the same argument.

This idea likely does not apply in a confrontation with a smaller power, such as North Korea, but it’s newly relevant today as the U.S. considers the future of its intercontinental ballistic missile program.

Where are the nukes?

The 90th Missile Wing was activated with a headquarters in Francis E. Warren Air Force Base in 1963. NPR reported in 2014 that the nuclear missile base has 150 missiles spread across a “missile field” around the intersection of Nebraska, Wyoming and Colorado, employing roughly 3,000 people.

For a time, the base hosted 50 “Peacekeeper” missiles, which could deliver 10 independently targeted warheads, each many times more powerful than the bombs dropped in Japan. It’s now home to 150 Minuteman IIIs, which only have one reentry vehicle each.

One of the silos, located in the fields west of the town of Peetz, recently made the news when three airmen accidentally did $1.8 million of damage to a nuclear missile there. There also are a half-dozen abandoned Titan silos much closer to Denver.

There’s an important debate about nuclear weapons happening right now.

The U.S. is considering spending $85 billion to modernize its intercontinental ballistic missiles.

Critics of the plan say that the U.S. could shift its nuclear missiles to submarines and bombers, making the mainland less of a target. Former Defense Secretary William Perry has called for “phasing out the entire land-based ICBM force.” (Here’s a fuller explanation of the argument against ICBMs.)

Current Defense Secretary James Mattis doesn’t seem so sure about that. He has specifically described the silos in the West as a crucial deterrent. The argument is that land-based silos are more reliable and faster than the alternatives, making them a better deterrent. And if you’re going to have silos, you would logically put them in the least populated parts of the country.

“It’s clear they are so buried out in the central U.S. that any enemy that wants to take us on is going to have to commit two, three, four weapons to make sure they take each one out,” Mattis said in written testimony to the Senate.

“In other words, the ICBM force provides a cost-imposing strategy on an adversary. What we’re trying to do is set such a stance with our triad that these weapons must never be used.”

How does North Korea relate to this?

Not too much.

There are reports that North Korea may have made a nuclear warhead that could be mounted on a missile, and it also has made a missile that may be able to reach Denver and most other American cities. President Donald Trump today threatened “fire and fury like the world has never seen” if North Korea keeps developing the weapons.

There are caveats: First, we don’t know if North Korea has missiles that can actually survive the journey to a target, and we don’t know how accurate they are. It may be some time — or forever — before the country has a reliable ICBM.

Also, North Korea is a vastly different threat than Russia ever was. While Russia could put hundreds of missiles into the air, North Korea would have no hope of winning a full nuclear war with the United States — if anyone really “wins” something like that.

Rather than taking out our nuclear arsenal, North Korea’s logical aim might be to use the threat of nuclear war to, say, have sanctions dropped. And Denver might not make as much sense to Pyongyang as, for example, the U.S. military bases in South Korea or Japan or Guam or the West Coast of the United States.

There’s also the fact that, according to the Ploughshares Fund, the missiles stashed in the West couldn’t realistically be used against North Korea, due to the fact that they’d have to fly over Russia.

However, if you want to take them at their word, North Korea has said it would use nukes against the U.S. if militarily provoked, and it has said it will not negotiate on its missile and nuclear weapons programs.