North Korea has a closer relationship with China because both of those countries have, at some point in their history, implemented a communist regime. Also, during the Korean war, the United States were very involved which could cause a feeling of animosity between the U.S. and North Korea.
Making a thing or person American.
The open door policy was designed to open Japan to American trade and influence (The US was hungry for an imperial puppet).
WOW!? That's a lot of questions....:(
