North Korea test fired two "strategic cruise missiles" from a submarine near Kyongpho Bay off the country's east coast late on Sunday, according to North Korean state media and South Korea's Yonhap News Agency. 

The drill was carried out in response to "anti-DPRK military maneuvers" by "the U.S. imperialists and the South Korean puppet forces," the state-run Korean Central News Agency (KCNA) said. 

"The drill confirmed the reliability of the weapon system and examined the underwater-to-surface offensive operations of submarine units that constitute ones of other major forces of the DPRK nuclear deterrent," the KCNA said in a statement. 

South Korea's military confirmed that they detected the launch of an "unspecified missile" by North Korea, saying that they are "maintaining a full readiness posture in close cooperation with the United States," the Yonhap News Agency reported. 

NORTH KOREA THREATENS ACTION AFTER US FLIES NUCLEAR-CAPABLE B-52 BOMBER OVER KOREAN PENINSULA

The U.S. is holding joint military drills with South Korea over an 11-day period starting Monday. The exercise, known as Freedom Shield, will "increase the units’ combat readiness and combined defense posture," United States Forces Korea said. 

North Korea dictator Kim Jong Un oversaw a mock attack on South Korea on Friday, instructing his country's military to prepare in response to "frantic war preparation moves" from the nation's enemies.

Fox News Digital's Timothy Nerozzi contributed to this report.