I'm pretty sure once the Japanese satellite got fried, they will let the US military know. Most of the time, we know each side capabilities. It doesn't get out to the public very often.
Wow if we are able to do this, we will be able to monitor all aircraft on air, submarine under water, tank on the surface over across half of the earth surface at one time. That is talking about a military advantage standpoint.
From a scientific, obviously we can monitor mother nature and...
There is no such thing as a bad technology. Even old technology can show you about the development your rival were working on. So you can create better and neutralize it.
Beside the practical use of quantum mechanical understanding on technology, it will also have a profound implication on life and the universe law at large.