WEll China is a signatory to the NPT,so in purely legal terms,they have every right to buy it from anyone inc.the US.
Its a small matter about whom they will hawk it in turn to!!
Thats why the NPT is such a non-productive treaty
For China to have that right and India not having the right exposes the sham that it is. China also has responsibilities
under NPT which they ignore and the other idiot nations in that treaty dont hold them accountable.