The United States showed an unprecedented display of force toward North Korea this week.
U.S. officials said two American B-2 stealth bombers with nuclear capability dropped munitions on the Korean Peninsula as part of joint military drills Thursday.
"The United States is steadfast in its alliance commitment to the defense of the Republic of Korea, to deterring aggression, and to ensuring peace and stability in the region," U.S. Forces Korea said in a statement.
The training mission comes amid threats from North Korea that includes nuclear strikes on Washington and Seoul.
The North sees the military drills as part of a U.S. plot to invade the communist nation. But Washington and Seoul say the annual drills are routine and defensive.