'Disproportionate' in What Moral Universe?

In today's Washington Post, Charles Krauthammer is simply excellent:When the United States was attacked at Pearl Harbor, it did not respond with a parallel "proportionate" attack on a Japanese naval base. It launched a four-year campaign that killed millions of Japanese, reduced Tokyo, Hiroshima and Nagasaki to cinders, and turned the Japanese home islands into rubble and ruin.Disproportionate?