The top office on Sunday downplayed North Korea’s recent claims of an underwater nuclear weapon system test as “exaggerated and fabricated.”

The statement came two days after Pyongyang said on Friday that it had conducted a test of the underwater weapon system called the “Haeil-5-23” in the East Sea in response to the recent maritime drills between South Korea, the U.S. and Japan.

The presidential office said that the test, if it occurred, is presumed to have involved a type of torpedo rather than a nuclear-powered system, which it said is highly improbable given that there is no reactor capable of fitting onto a torpedo with a diameter of less than one meter.

The office also stressed that the South Korean military already possesses the ability to overwhelmingly strike the launch sites of such weapons systems, adding that it will further strengthen its anti-submarine capabilities and defense posture for ports.