North Korea isn't fighting in Europe and never has, that's a fabrication of your own making.
You seem to be missing the massive North Korean combat losses and the formal ceremonies of war allies Putin and Kim Jong Un honoring the North Korean war dead from Europe.
As far as why the American president would be talking to hostile world leaders, especially Red China’s, you must be kidding about asking that.
Putin hails ‘brave’ North Korean troops, as Kim opens memorial for those killed in Ukraine war
“Balloons fly as soldiers stand in position next to memorial stones during the opening ceremony of the Memorial Museum of Combat Feats at the Overseas Military Operations honouring North Korean troops killed while fighting for Russia in the war against Ukraine, in Pyongyang, North Korea, on Sunday.”
https://www.theglobeandmail.com/world/article-russia-ukraine-war-north-korean-troops-memorial-putin-kim/