Nuclear weapons:

In the Aug. 10 Section A, an article about the challenges of a successful nuclear strike misstated the date the U.S. dropped an atomic bomb on Hiroshima, Japan. It was Aug. 6, 1945, not Aug. 9. Also, the article said the first fullscale demonstration of a thermonuclear weapon created a blast equal to 19 megatons of TNT. The blast was equal to 10 megatons.