Casus Belli and Iran
Some people have observed that Iran's seizure of British soldiers would at most points in history be considered casus belli, and perhaps at least lead to naval blockade.
While I don't entirely disagree with the idea that some people consider what I would call cowardice a virtue, I don't think it completely explains the blasé attitude this is meeting with. I think there's a strong non-political component to it as well.
Western societies have grown by leaps and bounds over the past several hundred years. It takes a lot more to get our attention than it used to, because we are a much bigger society, and I think a strong case can be made that this is a perfectly rational outlook. A two-inch cut on a small child can be a big deal; the same cut on me is an annoyance. If the West went to war over every two-inch cut, we'd be in full-scale war, all the time; there's always another grievance to be converted to casus belli.