The New York Times reports that "the United States flew a nuclear-capable B-52 long-distance bomber over South Korea on Sunday in a show of force after North Korea’s fourth nuclear test."
"The bomber, taking off from the United States Air Force base in Guam, arrived over Osan Air Base south of Seoul, the South Korean capital, on Sunday to conduct training missions together with American and South Korean warplanes, both countries’ militaries announced. The bomber returned to Guam after the exercise."
“'This was a demonstration of the ironclad U.S. commitment to our allies in South Korea, in Japan, and to the defense of the American homeland,' Adm. Harry B. Harris Jr., commander of the United States Pacific Command, said in a statement. 'North Korea’s nuclear test is a blatant violation of its international obligations.'”