The sad fact is that international politics has always been a ruthless and dangerous business, and it is likely to remain that way. - John Mearsheimer

We have a huge amount of evidence that it was nato expansion and the more general policy of making Ukraine a western bulwark on Russia’s border that motivated him to attack on February 24th... For Putin to have said time after time that nato, that Ukraine in nato, was an existential threat to Russia, when in fact it wasn’t, and this was all done to disguise the real motive, which was to incorporate Ukraine into a greater Russia for the purposes of satisfying his imperial ambitions is an argument that is just not supported by the historical record. Putin was very clear, as were all his lieutenants, that their great fear was that Ukraine was becoming a Western bulwark on Russia’s borders. For them, that was an existential threat. It was simply unacceptable.

The cycle of violence will continue far into the new millennium. Hopes for peace will probably not be realized, because the great that shape the international system fear each other and compete for power as a result. Indeed, their ultimate aim is to gain a position of dominant power over others, because having dominant power is the best means to ensure one's own survival.

This self-defeating behavior, so the argument goes, must be the result of warped domestic politics.