How significant is Xi Jinping's visit to North Korea?

Chinese president is in North Korea. Pyongyang is largely isolated on the world stage and under UN sanctions. China remains its main supporter. It's been sidelined due to its nuclear activities. But Pyongyang has made it clear it wants to be recognised as a nuclear state - and insists its programme is a "line of no retreat". Xi Jinping's visit comes after he held a summit with Donald Trump, who wants North Korea to denuclearise. He also met Vladimir Putin, who has been developing a closer relationship with Kim Jong Un. So, how could his visit shape geopolitics in the region?