Preparing for war: South Korea, U.S. respond to North Korea's threats

South Korean Army soldiers work on their K-9 self-propelled artillery vehicle during an exercise against possible attacks by North Korea near the border village of Panmunjom in Paju, South Korea, Monday, March 11, 2013. South Korea and the U.S. on Monday kicked off an annual military drill amid worries about a possible bloodshed following North Korea’s threat to scrap a decades-old war armistice and launch a nuclear attack on the U.S. (AP Photo/Ahn Young-joon)

South Korean protesters shout slogans near a huge banner with a picture of North Korean leader Kim Jong Un during a rally denouncing North Korea's recent threat and supporting South Korean President Park Geun-hye, seen in a picture on the left side of the top banner, near the presidential Blue House in Seoul, South Korea, Monday, March 11, 2013. South Korea and the United States began annual military drills Monday despite North Korean threats to respond by voiding the armistice that ended the Korean War and launching a nuclear attack on the U.S. (AP Photo/Lee Jin-man)

South Korean Army soldiers work on their K-9 self-propelled artillery vehicles during an exercise against possible attacks by North Korea near the border village of Panmunjom in Paju, South Korea, Monday, March 11, 2013. South Korea and the U.S. on Monday kicked off an annual military drill amid worries about a possible bloodshed following North Korea’s threat to scrap a decades-old war armistice and launch a nuclear attack on the U.S. (AP Photo/Ahn Young-joon)

South Korean President Park Geun-hye, center, presides over a cabinet meeting at the presidential Blue House in Seoul, South Korea, Monday, March 11, 2013. South Korea and the United States began annual military drills Monday despite North Korean threats to respond by voiding the armistice that ended the Korean War and launching a nuclear attack on the U.S. (AP Photo/Do Kwang-hwan, Yonhap) KOREA OUT

South Korean Army soldiers work on their K-9 self-propelled artillery vehicles during an exercise against possible attacks by North Korea near the border village of Panmunjom in Paju, South Korea, Monday, March 11, 2013. South Korea and the U.S. on Monday kicked off an annual military drill amid worries about a possible bloodshed following North Korea’s threat to scrap a decades-old war armistice and launch a nuclear attack on the U.S. (AP Photo/Ahn Young-joon)

South korean Army soldiers set up barbed wire fence during an exercise against possible attacks by North Korea near the border village of Panmunjom in Paju, South Korea, Monday, March 11, 2013. South Korea and the U.S. on Monday kicked off an annual military drill amid worries about a possible bloodshed following North Korea’s threat to scrap a decades-old war armistice and launch a nuclear attack on the U.S. (AP Photo/Ahn Young-joon)

South Korean protesters wearing masks hold placards during a rally denouncing the annual joint military exercises, dubbed Key Resolve and Foal Eagle, between South Korea and the United States, near the U.S. Embassy in Seoul, South Korea, Monday, March 11, 2013. South Korea and the United States began annual military drills Monday despite North Korean threats to respond by voiding the armistice that ended the Korean War and launching a nuclear attack on the U.S. (AP Photo/Lee Jin-man)

South Korean protesters wearing masks hold placards during a rally denouncing the annual joint military exercises, dubbed Key Resolve and Foal Eagle, between South Korea and the United States, near the U.S. Embassy in Seoul, South Korea, Monday, March 11, 2013. South Korea and the United States began annual military drills Monday despite North Korean threats to respond by voiding the armistice that ended the Korean War and launching a nuclear attack on the U.S. The letters read "When the war occurs, all 70 million people will die." (AP Photo/Lee Jin-man)

A South Korean protester holds a sign during a rally denouncing the annual joint military exercises, dubbed Key Resolve and Foal Eagle, between South Korea and the United States, near the U.S. Embassy in Seoul, South Korea, Monday, March 11, 2013. South Korea and the United States began annual military drills Monday despite North Korean threats to respond by voiding the armistice that ended the Korean War and launching a nuclear attack on the U.S. (AP Photo/Lee Jin-man)

South Korean protesters attend a rally denouncing the annual joint military exercises, dubbed Key Resolve and Foal Eagle, between South Korea and the United States, near the U.S. Embassy in Seoul, South Korea, Monday, March 11, 2013. South Korea and the United States began annual military drills Monday despite North Korean threats to respond by voiding the armistice that ended the Korean War and launching a nuclear attack on the U.S. (AP Photo/Lee Jin-man)

A South Korean protester wearing a mask holds a placard with a map of Korean peninsular during a rally denouncing the annual joint military exercises, dubbed Key Resolve and Foal Eagle, between South Korea and the United States, near the U.S. Embassy in Seoul, South Korea, Monday, March 11, 2013. South Korea and the United States began annual military drills Monday despite North Korean threats to respond by voiding the armistice that ended the Korean War and launching a nuclear attack on the U.S. (AP Photo/Lee Jin-man)