I just wanted to note the origins of the term.
Otto von Bismarck, chancellor (in German,
Ministerpräsident or
Reichskanzler*) of
Prussia beginning in 1862, coined the term to refer to blatant
power politics. Very much in the style of
Cardinal Richelieu of an earlier
France, Bismarck deliberately ignored similarities of taste, government, and values in his choice of allies, instead focusing on national interests. This abandonment of principle as a guiding force in foreign policy was both unusual in the context of 19th-century
Europe and quite powerful (as ought to be expected of a focus on power).
The term seems to be used most often in the United States today in a derogatory fashion, to suggest that the one so accused lacks principles or strength of character.
The information in this writeup comes from Henry Kissinger's 1994 book Diplomacy (published by Simon & Schuster, ISBN 0-671-65991-x).
I am told by ilteroi that Bismarck's title was actually Reichskanzler. This term does not seem to appear in Diplomacy, but both terms are well-attested by numerous websites. In any case, it certainly seems as though the more direct translation of 'chancellor', which is preferred by many as his title, is Reichskanzler. I am indebted to ilteroi for the correction.