This is a tech experiment. It may lead to advances in airplanes, but I highly doubt it is cost-effective compared to an equivalent missile that just slams home.
But apparently state of the art re-entry vehicles are capable of much more complex maneuvers including 180 degree turns (heading on ground, not the full 3d vector obviously).
The US has had this capability since a research project in the 1980s. Some form of it is deployed on Trident as well as the comparable UK and CH systems.
There is very little published on the topic, but if you start researching the AMaRV project you'll find some details and claims. Of course there's really no way for someone outside the defense community to confirm these claims, but I know of no physical reason why they couldn't be true.
now, to add to that: the radius of a 1 g turn at mach 20 is 4444 km. The radius of the earth is 6378 km. They've got to at least consider orbital mechanics just to hold altitude constant. Able to maneuver and highly maneuverable are two different things. The Titantic was able to maneuver. Just couldn't move fast enough.
Now, let's think about some other fun stuff, everybody join in.
Here's one: at mach 20, you need something along the lines of the shuttle's thermal protection system. We're talking plasma hot. Wrap this thing up in 3 inches of glass and I'll bet you've lost significant payload volume.
Same principle as a http://en.wikipedia.org/wiki/Railgun where projectiles travel at 5,400 mph, and the gun can be situated on an aircraft carrier.
On that note, the article above mentions railguns as way to launch spacecraft into orbit: applicable for this Mach 20 plane.
Mostly the letter "B" for "ballistic".
You can turn while flying. You can't turn while falling. You can stick out a little control vane to try to change course a little bit, but at that sort of speed, in that sort of atmospheric density, and bearing in mind that during re-entry anything that is at all pointy will get burned off, I doubt you could do much at all.
That this was a "plane" is inconsequential, and not even interesting, in terms of missiles - that they had at least minimal control at that speed is either a breakthrough, or duplication of existing techniques that can be applied to big-ass missiles (there, swap the B with "Big") more easily and more cheaply than to something designed to be re-used. Which, given the difficulty in adding controllable movement at such speeds to something way more complex than a one-use missile, implies to me that the techniques have existed for a while in cheaper forms, and this is just the first time they've been able to do it and (nearly) recover the device.
That's significant, but it's not a game-changer for missiles or making things go boom.
Ah, but then you're no longer falling.
You're not even "falling with style".
2. The US already has long-range assassination hit squads, e.g. Osama Bin Laden's Assassination
Plus its non-ballistic flight path and high degree of maneuverability probably allows it to evade most anti-aircraft and anti-ballistic missile defenses.
Scary stuff.
Edit: Grammar and spelling.
In either case, it seems moot in today's day and age. What's the difference between firing a missile at enemy headquarters with the intention of killing the general and senior staff, and an assassination?
It seems today that 'assassination' is simply pursuing the usual methods of war against a specific target.
There were no basis for the accusations but he understandably pretty unhappy as the penalties for being found guilty could be pretty severe.
You hear the scream of a missile overhead. It passes. Sometime later you will die.