the united states did not at all get involved in world war one, other than shipping supplies overseas to help allied countries.....
the U.S. did not enter into a(n) global warfare conflict until world war 2, because of japan's bombing, and destruction of pearl harbor, and several allied naval bases/ports.
Only the federal government can regulate interstate and foreign commerce, declare war and set taxing, spending and other national policies.
D. Breakup of Soviet Union in 1991. This caused areas of land to be unclaimed, which new countries then formed in.
