This is the People's Republic of China. Their disputed territorial claims amount to a few villages claimed by India and a few small islands claimed by Japan and Vietnam. All three countries have much bigger territorial disputes with other countries. You're thinking of The Republic of China, who claims whole countries and very large swaths of land. The Republic of China doesn't have a seat in the UN because they don't have majority support. (1.4% vs 98.6% for PRC).

They do own. Just because one side reneged on the agreement when it was their turn to pay doesn't make their ownership any less valid. So many of you are "lets just let the US do whatever the fuck they want, even if it breaks every law and treaty in the process" and it shows.