North Korea test-fired two strategic cruise missiles from a submarine in a show of force hours before the United States and South Korea were to stage major joint military exercises, state media reported early on Monday.
A submarine fired the weapons from waters off the eastern coastal city of Sinpo on Sunday morning, the KCNA news agency said.
The South Korean military said it detected the launch of a single unspecified missile, without giving details, the Yonhap news agency said.
KCNA said the drill was successful, as the missiles hit their designated and unspecified targets in waters off the east coast of the Korean Peninsula.
The launch came hours before South Korea and the United States were set to kick off their largest joint exercises in five years on Monday. Nuclear-armed Pyongyang has warned such drills could be seen as a "declaration of war".
The KCNA report announcing Sunday's missile launch said the test firing expressed "the invariable stand" of North Korea to confront a situation in which "the US imperialists and the South Korean puppet forces are getting ever more undisguised in their anti-DPRK military maneuvers."
DPRK is the acronym for North Korea's official name.
KCNA said the drill also "verified the current operation posture of the nuclear war deterrence means in different spaces."
In a separate statement, North Korea's foreign ministry said the United States was "scheming" to call a UN Security Council meeting on human rights in the reclusive communist state, to coincide with the joint maneuvers.
"The DPRK bitterly denounces the US vicious 'human rights' racket as the most intensive expression of its hostile policy toward the DPRK and categorically rejects it," the ministry said, according to KCNA.
