Re: The fragile nature of the Klingon/UFP "alliance"?
The Klingons were originally created as metaphors for the Soviets of course, and with glasnost Star Trek did a similar parallel.
Another way to look at the thawing of relations between the Federation and the Klingons, is as when the first Europeans were venturing into North America, from the perspective of both sides.
Dr. Howard, Dr. Fine, Dr. Howard: For Duty and Humanity!
--Men in Black, 1934.