While I am no fan of China's government we have to accept that if a foreign power were flying over our own airspace without permission we would do the same. Drones make it a lot easier politically to shoot down than a piloted aircraft but the principle remains the same. Perhaps USA has got used to being able to invade the airspace of anyone they feel like but we cannot complain if the country in question defends itself.
China has the right to shoot down drones if they see them as a threat. I am very uneasy about drones and their ability in invade privacy. The owner of the drone should be responsible for where it flies and if it goes into airspace that is restricted then bye-bye drone.
While, I do believe there is a benefit to the US to have and use drones in matters of national security, I also believe that it is the right of other countries to defend themselves. In this case, if China believes that the US is using drones to spy on their country or to attack their country, then they have the right to shoot down those intruding devices.
A laser cannon? That sounds incredibly scary, kind of like a version of Dr. Evils laser beam.... What kind of drones are they shooting down? Nosy American ones? Dangerous ones? Or just any drones? I don't like the drones either, I think they are invasive and ridiculous. Both of those things make me nervous