Many states with young populations are growing old fast. If states with older populations engage in violent conflict less frequently than states with large numbers of young people, the implications for the international order could be significant. 

Charles L. Glaser, Andrew H. Kydd, Mark. L. Haas, and John M. Owen IV respond to Sebastian Rosato's winter 2014/15 article, "The Inscrutable Intentions of Great Powers."

The world's great powers are growing old. Steep declines in birthrates over the last century and major increases in life expectancy have caused the populations of Britain, China, France, Germany, Japan, Russia, and the United States to age at a substantial rate. This phenomenon will hinder the other major powers challenging America's economic and military dominance, largely because these countries are growing old faster than is the United States. Yet population aging may still threaten America's international security interests.

Mark L. Haas wrote "America's Golden Years?" which was published on August 30, 2007, in the Boston Globe.

"The world's great powers are growing old. Steep declines in birthrates over the last century and major increases in life expectancy have caused the populations of Britain, China, France, Germany, Japan, Russia, and the United States to age at a substantial rate. This phenomenon will hinder the other major powers challenging America's economic and military dominance, largely because these countries are growing old faster than is the United States. Yet population aging may still threaten America's international security interests."

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