North Korea has carried out tests on a new nuclear-capable underwater drone, according to state media reports on Friday. This comes as the country's leader, Kim Jong Un, called for an end to joint military exercises conducted by South Korea and the United States.

The North Korean drone was tested in waters off the east coast, traveling at depths of 80-150 meters (260-500 feet) for over 59 hours before detonating a non-nuclear payload, as reported by North Korean state news agency KCNA.

Analysts believe that North Korea aims to demonstrate its growing range of nuclear threats to Washington and Seoul, though there is skepticism about the underwater vehicle's readiness for deployment. Ankit Panda, a senior fellow at the US-based Carnegie Endowment for International Peace, stated that North Korea is sending a message "to the United States and South Korea that in a war, the potential vectors of nuclear weapons delivery that the allies would have to worry about and target would be vast."

On Monday, North Korea launched a short-range missile from a concealed silo, differing from its usual basing methods. The new drone system, named "Haeil" or "tsunami," is designed for stealth attacks in enemy waters, with the goal of destroying naval strike groups and significant operational ports through underwater explosions, according to the KCNA.

South Korean and US officials are analyzing North Korea's claims, and it remains uncertain whether North Korea has successfully developed miniaturized nuclear warheads for its smaller weapons.

The recent tests coincide with the largest amphibious landing drills between South Korean and US forces in recent years. North Korea has long been critical of such exercises, claiming they are preparations for an invasion of the North. In response, South Korea and the US maintain that the exercises are purely defensive and have criticized North Korea's tests as destabilizing and in violation of UN sanctions.