Basically, not everyone desired a strong central government
after the revolution, which was not being under the leadership of a strong
central government. The constitution confines the influences of the federal
government but it has been fragmented, because the people no longer want to be accountable
for the argument of their privileges.
It is a cause because the effect is America entering the World War. They "found" the Zimmerman Note and got "angry" because they were teaming up as an alliance against America.