Washington says the participation of two B-2 bombers in the South Korea-U.S. combined Foal Eagle drill is for defensive purposes.

White House Deputy Press Secretary Josh Earnest said at a briefing Thursday that South Korea and the U.S. conduct a range of military exercises on an annual basis that are defensive in nature and drills that include B-2 bombers are just one of those exercises.

State Department Spokeswoman Victoria Nuland also said that the use of such aircraft is to strengthen the U.S. missile defense against the North Korean threat.

Earlier on Thursday, the South Korea-U.S. Combined Forces Command confirmed that the two B-2 bombers took part in a bombing drill on the Korean Peninsula. The B-2 stealth bomber, which only registers on radar as the size of a small bird, is one of the U.S. military's most deadly strategic weapons.