North Korea on Saturday threatened to confront planned US-South Korean military exercises with "nuclear deterrence," according to the National Defence Commission - the highest decision- making body in the country, dpa reported.
Earlier this week, the US State Department said North Korea would be "very unwise" to counter the exercises that are scheduled to begin on Sunday.
The United States and South Korea are conducting the exercises following a determination that Pyongyang was responsible for the March sinking of a South Korean warship in which 46 sailors died.
The exercises, formally announced Wednesday while US Secretary of State Hillary Rodham Clinton and Defence Secretary Robert Gates were in Seoul, are designed to enhance capabilities between both sides and send a message that the United States is committed to South Korea's security.
The US Navy is capable of defending itself and "clearly it would be very unwise for North Korea to challenge these forces," a State Department spokesman said.
North Korea, which denies any role in the sinking of the Cheonan, has said it viewed the exercises as threatening.
While in Seoul, Clinton announced the tightening of sanctions against the Stalinist state.