New Delhi, Feb. 26 -- The U.S. and South Korean militaries said on Wednesday they will conduct their annual springtime exercises next month to bolster their countries' combined defense capabilities against a backdrop of a deepening diplomatic freeze with nuclear-armed North Korea.

The Freedom Shield drills is set for March 9-19, according to the announcement.

North Korea has long described the allies ' joint exercises as invasion rehearsals and used them as a pretext to dial up its own military demonstrations and weapons testing activity. The allies say the drills are defensive in nature.

The announcement came as North Korea is holding a major political conference where authoritarian leader Kim Jong Un is expected to outline his key do...