New strands? I'd argue that WW I and WW II (at least in Europe, with the Asian theatre built on a similar but indeed newer problem). "The Germany Problem"; namely how the European order was going to integrate the historically-sudden formation of a new, populous, industrial and military superpower without displacing the vital interests/status and feelings of security in the existing hegemons to the point they feel the need to respond in a threatening way, which leads to a downward spiral. The same thing happened in a way with Napoleon. Prior to WW 1, the 2nd Age of Imperialism and restraint of Bismarck and other key statesmen allowed these moves to be played out by carving out the rest of the world to maintain some semblance of balance of power and allow nations to negotiate through tensions without actually having to sacrifice anything themselves, but by 1914 the world was getting too crowded both colonially and economically for that to work anymore.