What Is an ICBM? North Korean Missile Went Further Into Space Than the International Space Station

north korea ICBM
This July 28 photo released by North Korea's official Korean Central News Agency shows North Korea's intercontinental ballistic missile, Hwasong-14, being launched at an undisclosed place in North Korea. STR/AFP/Getty Images

Early reports about North Korea's missile launch on Tuesday suggested that the rocket was an intercontinental ballistic missile. According to an analysis from the Union of Concerned Scientists' Global Security Program co-director and senior scientist, David Wright, "if flown on a standard trajectory rather than this lofted trajectory, this missile would have a range of more than 13,000 kilometers."

This is based on reports suggesting the missile went more than 4,500 kilometers, or 2,700 miles, into space; for comparison, the International Space Station is orbiting 400 kilometers, or about 250 miles, above Earth, according to NASA.

"Such a missile would have more than enough range to reach Washington, D.C., and in fact any part of the continental United States," Wright noted.

Statement by #Pentagon spokesman Col. Robert Manning on #NorthKorea launch: The @DeptofDefense detected and tracked a single North Korea #missile launch today at about 1:17 p.m. EST.
Details: https://t.co/NKByy0IxQP

— Jonathan Hoffman (@ChiefPentSpox) November 28, 2017

By definition, ICBMs travel at least 5,500 kilometers—about 3,400 miles—Wright told Newsweek. Only a small part of the missile is cause for fear: "A ballistic missile is basically 90 percent fuel," Wright said. Of the three stages of an ICBM, two are made up of fuel and engines; the other, the warhead, actually carries the bomb. There are two fuel-heavy stages because it wouldn't make sense drag along an empty fuel tank for a missile's entire trajectory.

North Korea also launched an ICBM in July in a similarly steep arc, Wright noted, but the missile launched Tuesday is thought to have a slightly different second stage, which may explain why it travelled further, Wright speculated.

"'Ballistic missile' typically means a guided missile whose engines burn for a short period of time at the beginning and release. It travels like if you're throwing a baseball," Wright explained. Once the ball is thrown, it will travel until gravity pulls it down. While an ICBM's flight might last more than 30 minutes—a lot longer than any pitch—the engines that power that flight might burn for only five minutes. "After it burns out, you're basically relying on the idea that you've aimed it well enough that you'll hit close to your target," Wright said.

Aiming an ICBM gets more difficult as the target gets farther away, which can influence which targets make most sense for these missiles. Very small targets are extremely difficult to hit because even small inaccuracies can lead to a missile landing miles off-course. "That means that if I'm North Korea and I develop a long-range missile, even if I have a nuclear warhead on it, I'm not going to be able to shoot at a small target like a military site," Wright said. A large population center—like Los Angeles—would make a better target.

Though this particular missile might have been able to reach major U.S. cities on its trajectory, that doesn't mean it's time to start building bunkers in New York. "When we've done our best to understand what the capabilities of the missiles are, we don't think it could carry a very heavy payload to that range," Wright said. "We don't know how lightweight a nuclear warhead they could make, and we don't really know the details of their missiles to know how far they could carry that warhead even if we knew the mass."

Though the fact that North Korea is launching ICBMs that could reach the East Coast may be shocking, Wright said the country's overall efforts to develop these missiles didn't surprise him. "I've been watching this missile program for 25 years now," he said. "This is old technology, but there is very little doubt. North Korea had the cookbook, they knew what other countries had done. As long as they could build up their engineering capability, it was clear where they were headed."