You’ve probably seen the grainy footage of a Minuteman III roaring out of a silo in North Dakota or a Russian Sarmat punching through the clouds. It looks fast, sure. But "fast" doesn't really cover it. When we talk about how fast an ICBM flies, we aren't talking about "sports car" fast or even "jet fighter" fast. We are talking about speeds that literally turn the air around the missile into a sheath of glowing incandescent plasma.
An Intercontinental Ballistic Missile (ICBM) doesn't just fly; it hurls itself into the vacuum of space and then falls back down with the purposeful violence of a meteor. If you were standing in New York and someone launched a missile from Moscow, you'd have about 30 minutes to figure out your life.
The Three Stages of "Fast"
To understand the speed, you have to realize that an ICBM is basically a giant fuel tank that spends most of its life trying to get rid of itself. It doesn't have one single speed. Instead, it goes through a terrifying acceleration curve.
1. The Boost Phase (The Heavy Lift)
This is the first three to five minutes. The missile is fighting gravity and the thick, soupy air of the lower atmosphere. It’s actually at its "slowest" here, but it's still pulling away from the Earth at several kilometers per second. By the time the final stage burns out, the missile is moving at roughly 15,000 mph (24,140 km/h).
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2. The Midcourse Phase (Space Coasting)
Once the engines quit, the missile is in the vacuum of space. There is no air to slow it down. This is where the ICBM reaches its peak velocity. For a modern American Minuteman III or a Russian RS-28 Sarmat, we are talking about Mach 23 or higher. That is roughly 17,500 miles per hour.
At this speed, you could travel from San Francisco to Washington D.C. in about 8 minutes. You aren't "flying" anymore; you are in a sub-orbital trajectory. You're basically a temporary moon.
3. Reentry (The Fiery Return)
This is the part that keeps engineers up at night. As the warhead (the Reentry Vehicle or RV) hits the atmosphere at 7 kilometers per second, the friction is insane. The air can't get out of the way fast enough, so it compresses and heats up to thousands of degrees.
Strangely, the missile actually slows down during reentry because of atmospheric drag. But "slowing down" is relative—it’s still hitting the ground at several times the speed of sound.
Comparing the Heavy Hitters: Who is Fastest?
Not all missiles are created equal. Some are built for raw speed to outrun interceptors, while others focus on carrying a massive "bus" of multiple warheads.
- LGM-30G Minuteman III (USA): The backbone of the US land-based triad. It hits about Mach 23. It’s old, but it’s a reliable sprinter.
- RS-28 Sarmat / "Satan II" (Russia): This thing is a monster. While its exact top speed is a closely guarded state secret, experts like those at the Center for Strategic and International Studies (CSIS) estimate it travels at least Mach 20.7, though some Russian sources claim it pushes higher when equipped with the Avangard hypersonic glide vehicle.
- DF-41 (China): Widely considered one of the fastest in the world, potentially reaching Mach 25. That is over 19,000 miles per hour.
Why Don't They Just Go Faster?
You might wonder, why stop at Mach 25? Why not Mach 50?
Physics has a "speed limit" for these things. If an ICBM goes much faster than 17,500 mph, it won't fall back to Earth. It will enter Low Earth Orbit (LEO) and stay there. To hit a target on the other side of the planet, you actually have to be "slow" enough to fall back down.
There's also the heat issue. At Mach 25, the leading edge of a warhead is dealing with temperatures that would melt most known metals. We use carbon-carbon composites and "ablative" shields—materials designed to burn away and carry the heat with them—just to keep the electronics inside from frying.
The Hypersonic Myth vs. ICBM Reality
People get confused between ICBMs and the "Hypersonic Missiles" you see in the news.
Technically, every ICBM is hypersonic because "hypersonic" just means anything faster than Mach 5. However, when the Pentagon talks about "hypersonic weapons," they usually mean Hypersonic Glide Vehicles (HGVs).
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An ICBM follows a predictable, high-arching path like a tossed football. A Hypersonic Glide Vehicle is launched on an ICBM but then "skips" along the top of the atmosphere, maneuvering like a high-speed glider. It might actually be slower than a traditional ICBM warhead, but because it can turn and dodge, it’s much harder to hit.
How to Visualize This Speed
It’s hard to wrap your brain around 4 miles per second.
- A commercial airliner flies at about 550 mph.
- A sniper bullet travels at about 1,700 mph.
- An ICBM travels at 17,500 mph.
If you were sitting in a stadium watching an ICBM fly past at its top speed, it would cross the entire field in about 0.01 seconds. You wouldn't even see a blur. You’d just hear a crack of thunder as the sonic boom shattered every window in the zip code.
The Reality of Interception
Can we stop something moving Mach 23? Sorta.
The U.S. Ground-based Midcourse Defense (GMD) system in Alaska and California is designed to hit a bullet with a bullet. To stop an ICBM, an interceptor has to launch and calculate a collision point in space. Because the speeds are so high, even a tiny calculation error of a microsecond means the interceptor misses by hundreds of meters.
It’s the most difficult engineering task humans have ever attempted. And honestly, it’s why the speed of these missiles remains the ultimate deterrent.
Next Steps for Understanding Strategic Tech
If you want to get a deeper handle on how these systems work, your best bet is to look into the trajectory mechanics of sub-orbital flight. You can use tools like the Federation of American Scientists (FAS) missile simulators to see how flight times change based on "lofted" versus "depressed" trajectories. Additionally, researching Ablative Cooling will give you a better respect for the materials science that keeps these machines from vaporizing the moment they touch the air.