China had been carved up by European countries & Japan into spheres of influence
Basically, European countries took over parts of China. Inside each sphere, China could only trade with that specific country & any citizens of that country who committed a crime in that sphere could not be prosecuted by China
Puerto Rico is a US commonwealth, a majority of Puerto Ricans prefer being a commonwealth rather than independent or the 51 st state.
As a Commonwealth, residents of Puerto Rico lack voting representation in Congress and do not participate in presidential elections. As U.S. citizens, Puerto Ricans are subject to military service and most federal laws.
US had trouble fighting a war against insurgents, both sides did unforgivable things
"We bombarded a place called Malabon, and then we went in and killed every native we met, men, women, and children. It was a dreadful sight the killing of those poor creatures. The natives captured some of the Americans and literally hacked them to pieces, so we got orders to spare no one."