Preemption is a kind of pre-deterrence that stops the threat at an earlier, safer stage.

Doves oppose war on the grounds that the risks exceed the gains. War with Iraq could be very costly, possibly degenerating into urban warfare.

Some geopolitical conflicts are morally complicated. The Israel-Gaza war is not. It possesses a moral clarity not only rare but excruciating. [...] For Hamas, the only thing more prized than dead Jews are dead Palestinians.

Clashes of values and the struggle for primacy constitute a constant in human history that accounts for that other constant - conflict and war.

Why should we care about the coup? First, because we depend on Yemen's government to support our drone war against another local menace, al-Qaeda in the Arabian Peninsula (AQAP). It's not clear if we can even maintain our embassy in Yemen, let alone conduct operations against AQAP. And second, because growing Iranian hegemony is a mortal threat to our allies and interests in the entire Middle East.

Americans are not intrinsically imperial, but we ended up dominant by default: Europe disappeared after the Second World War, the Soviet Union disappeared in 1991, so here we are.

Obama has committed the U.S. to war on the Islamic State. To then allow within a month an allied enclave to be overrun - and perhaps annihilated - would be a major blow.