Putin's 'invincible' missile has a very common problem

• Putin has touted Russian hypersonic weapons like the Zircon missile as impossible to defend against.
• Zircon in particular is powerful but there are limits on what it can do, a Western expert says.
• Like other high-speed weapons, the Zircon's velocity may come at the expense of its accuracy.

Russia's Zircon hypersonic missile can do two things: fly at almost 7,000 mph, which makes it very hard to shoot down, or hit a moving ship. But it can't do both.