The Pentagon's researchers at Darpa have also been experimenting with hypersonic glider.

Could an armed, hypersonic glider based on the finicky Hypersonic Test Vehicle replace the strike-anywhere nuke-less ICBM?

Most of the experiments center around a new type of warhead for the ballistic missile: a hypersonic glider.

If a standard warhead has an upside-down-U-shaped trajectory, the hypersonic glider's looks like a backwards-L. That's called "boost-glide" in missile jargon.