For those who are really interested in the topic of international relations as exercised by the US it would be of interest to study the US-UK relations especially beginning in the period just after WW I (rather from 1917). You might want to consider the Lease Lend scheme etc.
It would give some insights how the US interacts with allies....
I happen to have studied international relations,actually it had 3 credit hours in my degree and i studied the book International Relations by S.Goldstein .quite an interesting stuff it contains