New Delhi, March 11 -- North Korean leader Kim Jong Un and his teenage daughter observed tests of strategic cruise missiles fired from a warship, state media reported Wednesday, as North Korea threatened responses to U.S.-South Korean military drills.

Images sent by the Korean Central News Agency showed the two in a conference room looking at a screen showing weapons being fired from the Choe Hyon, a year-old naval destroyer.

Kim Jong Un watched the missiles launches via video on Tuesday and underscored the need to maintain "a powerful and reliable nuclear war deterrent," KCNA reported in a dispatch that did not mention his daughter.

The girl, reportedly named Kim Ju Ae and about 13, has accompanied her father at numerous prominent eve...