China will eventually perfect the J-20 and J-31, however—it is just a matter of time. “They are going get there one day, make no mistake,” the senior official said. “It won’t be tomorrow or the next day, but the fact this place is debuting now should tell you something about China’s commitment.”
The US has had problems keeping military and other secrets as seen by the Snowden and Wikileaks cases.
If the USA sold military planes to China, then China would of course reverse engineer them and fully utilize them in their own planes. However, the US makers could also arrange for China to be a primary source of parts for the planes.
China's airplanes and airplanes parts are less than half the cost of US manufacturers.
$400 billion has already been spent developing the F35 and it is expected to cost another $600 billion to $1 trillion to buy more F35 planes and operate them.
Arranging for China to buy the planes would also increase the market size for US production.
The US would not be losing much military advantage because China already has most of the technology.
The US would be in a better economic position with perhaps $500 billion less debt if the arrangement were made for F31 and F22s.
China is also able to afford to hire US, European plane designers and technical specialists.
Lockheed and other US military companies would still have their profit margin because they would be buying the lower cost parts and still marking it up.
The US tax payer would come out ahead.
The US companies would have more money to develop the new generation F-XX planes. The US could try to protect those secrets but will probably not be successful.
SOURCES - Seekingalpha, National Interest