The relative peace has had enormous benefits. Living standards have surged, with people living longer, healthier and more comfortable lives on average than their ancestors. In recent decades, the largest gains have come in lower-income countries. The decline in warfare has played a central role: By the start of this century, the rate at which people were dying in armed conflicts had fallen to the lowest level in recorded history, as Joshua Goldstein, Steven Pinker and other scholars have noted.
A Russian invasion of Ukraine would look like the kind of war that has been largely absent in the past 80 years and that was once common. It would involve a powerful nation setting out to expand its regional dominance by taking over a neighbor. A war like this — a voluntary war of aggression — would be a sign that Putin believed that Pax Americana was over and that the U.S., the European Union and their allies had become too weak to exact painful consequences.
New York Times, The Morning Newsletter