North Korea fired long-range cruise missiles into the sea to test its nuclear deterrence, following progress on its first nuclear-powered submarine.

The launches, praised by Kim Jong Un, were described as exercises in self-defense and war deterrence amid perceived external threats.

South Korea and the U.S. remain on alert, noting the missiles’ low-altitude, maneuverable capabilities could target warships and aircraft carriers.

The tests come ahead of North Korea’s ruling Workers’ Party congress and follow previous missile and anti-air launches, highlighting the country’s push to expand its nuclear and weapons capabilities, ABC News has reported.

Analysts suggest North Korea seeks to strengthen leverage in potential future negotiations with the U.S. while continuing to develop advanced weapons systems.