North Korea fired two “strategic cruise missiles” from a submarine in waters off its east coast over the weekend, the country’s state media said on Monday.

The North’s first known firing of cruise missiles from a submarine is widely viewed as an apparent show of force against a major South Korea-US combined military exercise, reports Yonhap News Agency.

The missiles were fired from the 8.24 Yongung in waters off Kyongpho Bay in the East Sea in an underwater launching drill held at dawn on Sunday, according to the North’s official Korean Central News Agency (KCNA).

“The drill confirmed the reliability of the weapon system and examined the underwater-to-surface offensive operations of submarine units that constitute one of other major forces of the DPRK nuclear deterrent,” the KCNA said in a report, using the acronym of the North’s official name.

The missiles precisely hit preset targets in the East Sea after “travelling the 1,500 km-long eight-shaped flight orbits for 7,563 to 7,575 seconds”.

The latest launch came on the eve of the start of the allies’ 11-day Freedom Shield exercise, which the North calls “preparations for a war of aggression” against it.

North Korea said its latest underwater launching drill “verified the current operation posture of the nuclear war deterrence means in different spaces”.

Earlier in the day, South Korea’s Joint Chiefs of Staff (JCS) said it detected an unspecified missile launched from a submarine in waters off the North’s eastern coastal city of Sinpo on Sunday morning.

It did not immediately provide other details.

Following the KCNA report on the launch, a JCS official said there is a “difference” between the North’s claim about the missile’s specifics and the analysis by the South and the US.

He did not elaborate, while his comments have indicated that the military views the reclusive North as having exaggerated the results of its latest cruise missile testing.

He characterized the North’s launch of the missiles as an “early-stage” test, indicating that the missile has not been deployed yet, speaking to reporters on the condition of anonymity

Cruise missiles fly low and maneuver, making them better at evading missile defenses. The North said last month it launched four “Hwasal-2 strategic cruise missiles” in a drill aimed at bolstering its nuclear counterattack capability.

Military experts assessed that the North appears to have improved the striking capability of its submarine.

If confirmed, a North Korean cruise missile with an operational range of some 1,500 km could target the whole of South Korea and US military bases in Japan.

The North’s push for the submarine-based launch platform reflects its ongoing efforts to diversify nuclear delivery vehicles and enhance their wartime survivability, the experts added.

The North is widely expected to conduct further weapon tests to protest the allies’ military exercises, as it has threatened to take “unprecedentedly strong” and “overwhelming” counteractions against what it called the US hostile policy.

At akey party meeting presided over by North Korean leader Kim Jong-un on Saturday, the North decided to take “important, practical” measures for the “offensive use” of war deterrents, according to the KCNA.