Robert Cooper is a career diplomat who is nowadays working for the European Council and directly responsible to Javier Solana (talking about a job I would want to do). His book (more like an essay really) The post-modern state and the world order was super interesting. It does not contain any ground-breaking (or maybe it did back then (1997), but it describes the post 1989 very, very accurately, including a prediction of the emergence of failed states and terrorist organizations harbored in these as a threat to the world.
Cooper separates the world in three parts. The post-modern world (basically the EU, to some extent the US) where the rule of law (based on self-restricting treaties) in inter-state interactions is dominant, military power is not a viable solution to problem-solving and borders are increasingly irrelevant. The modern world which describes the world as Machiavelli and Clausewitz knew it, with war a method of politics, borders subject to change, and traditional nation-states competing with each other (unlike the post-modern world where competition takes place more on an economic and individual level). Finally, the pre-modern world, which describes failed states such as Somalia and Afghanistan. These states, where no one holds a monopoly on violence, should in (cruel if you want) realpolitischen terms be left alone, since they cannot bother anyone. Yet, in today's society this is not possible due to two reasons. Firstly, the impact of newspaper reporting and popular pressure to act in case of suffering, murder or (worst of all) genocide. These interventions are usually very limited in nature, simply because it is difficult to estimate their true value for the intervening state (especially considering the flighty nature of public opinion which, after the death of a few soldiers, can rapidly swing against any intervention). Secondly, the aforementioned non-state actors who in an asymmetrical war can hurt virtually anyone (remember this was written before 2001).
A very descriptive, very good and accurate essay. Check it out if you care to find out more about the world as it is today.