A submarine fired the weapons from waters off the eastern coastal city of Sinpo on Sunday morning, North Korean state media said early on Monday.The South Korean military said it detected the launch of a single unspecified missile, without giving details.North Korean state media 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".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 manoeuvres.