china has most of weapon tech but not the equipments to make them...
it takes years to have a great overall industrial infracture to make good engines, high-quality steel and other modern equipments...even if u know how to make them does not mean u can make them..
that is the problem of chinese military, that is why China is consuming weapons from EU, which has a comprehensive and mature weapon industry, china's military industry is behind EU (although i believe on missile tech china is at state-of-art)...
lifting EU arm-embargo and selling weapons to China may actually cause U.S more troubles if there is really a war between U.S and China in Korea again....but that is highly unlikely right/?