The country is also modernizing its global navigation system to compete with those of the United States, Russia and Europe.

The United States has justified drone strikes in Pakistan, Yemen and Somalia by saying their governments have been unwilling or unable to suppress the threats from the individuals targeted.

American University law professor Stephen Vladeck says Washington needs to be much more specific about its conditions for using armed UAVs.

"Part of the problem is that because the U.S. government is engaged in what seems like so many drone strikes, and has not exactly been forthcoming about the criteria it uses, it's possible for countries like China to point at the U.S. example and say, 'if they're doing it, so can we.'"

The United States exports unmanned aircraft to only a few of its closest allies. China is now seen as an increasingly reliable and cheap supplier. Several countries have bought or built their own UAVs, mostly for surveillance. Professor Vladeck finds this concerning.

"The problem is that this technology is becoming so widely available and so cheap, that I think it is only a matter of time before countries with far smaller militaries, countries with far less responsible regimes, are in a position where they want to use these technologies as well."