I can not really comfirm but a reports few months again indicated new air shelter, north Korean pilot spotted training in China. There is never such practice NK pilot send to China for training or mock up exercise. The only conclusion from those observation is , they are send to China to train for new type of fighter.
China promised not to sell missile that exceed 300km under weapon proliferation back by UN resolution . And yet we know Saudi buys DF-21 missile and even received ToT of such missile from China.
NK is always a backyard for PRC and we signed a partnership treaty with NK that's makes China oblige to provide defense weapon to help NK defend itself against aggressor.
Yes, it is politically possible.
In 2009, China endorsed the UN Security Council resolution on arms embargo against North Korea for a reason.
In 2008, the economic crisis broke out in USA. China and USA reached an agreement, and China decided to intervene in the U.S. economic crisis. China's relations with USA have temporarily entered a period of friendship. China is ready to use this period to build a Northeast Asia free trade area with South Korea, Japan and Russia. However, North Korea's frequent missile tests undermine the situation in Northeast Asia and provoke Obama. China needs to give Kim Il Sung a warning.
In recent years, the attitude of North Korea has changed a lot. With the deepening of the agricultural cooperation agreement between China and North Korea in 2004, North Korea has got rid of the problem of famine. North Koreans have enough sense of security, and will not fear and undermine the economic exchanges between China and South Korea and other countries. I think China can consider relaxing the arms embargo on North Korea.
BTW: In January 2022, the UN's new sanctions agreement on North Korea was not adopted by the Security Council. Now USS is imposing unilateral sanctions on North Korea. On February 7, 2022, China has publicly opposed such unilateral sanctions.