Part 1
Aid is when a country needs medicine another country will send some to them when they need it, a treaty is when two countries sign something that makes peace with them or it can stop a war. And a alliance is when two or more countries agree to fight in a war and help each other during it.
Part 2
The U.S. isn't on the the diaphragm because they weren't fighting in the war when it started they joined it later into the war and they will be in the diaphragm later whenever they join. They joined the war because the president of the U.S. at that time ordered them to join and help their allies Britain, France, Russia, and Italy.
Aid is when a country needs medicine another country will send some to them when they need it, a treaty is when two countries sign something that makes peace with them or it can stop a war. And a alliance is when two or more countries agree to fight in a war and help each other during it.
Part 2
The U.S. isn't on the the diaphragm because they weren't fighting in the war when it started they joined it later into the war and they will be in the diaphragm later whenever they join. They joined the war because the president of the U.S. at that time ordered them to join and help their allies Britain, France, Russia, and Italy.