North Korean leader Kim Jong Un inspects new submarine that could potentially threaten US

SEOUL, South Korea -- North Korean leader Kim Jong Un inspected a newly built submarine on Tuesday as North Korean and U.S. negotiators wait to return to the bargaining table.

Korean Central News Agency (KCNA) reported that Kim expressed great satisfaction with the sub, and that he “stressed the need to increase the national defense capability by directing big efforts to the development of naval weapons and equipment such as submarines.”

The submarine will perform its duty in the operational waters of the East Sea, according to KCNA. The report did not include the size of the submarine, nor the dock yard in which the submarine was assembled.

In June, North Korea analysis website 38 North reported that, based on satellite imagery, North Korea was building a ballistic missile submarine at Sinpo South Shipyard.

Kim's comments on the new vessel send a message to President Donald Trump, analysts say. Although specific details regarding the giant sub have not been made public, the vessel could pose a threat to the U.S. mainland if its size turns out to be larger than 3,000 tons.

“North Korea is browbeating the U.S.,” Byun Sang-Jung, deputy president of the North Korean Studies Division at the South Korea-based Institute for National Security Strategy, told ABC News. “Kim is boosting its stance in the negotiations holding a big bargaining chip -- a submarine that can hold ballistic missiles.”

“We can make an intelligent assumption from the picture KCNA uncased that the submarine is large enough to be a military threat to the U.S.,” Shin Beom Chul, director at the Asian Institute for Policy Studies, told ABC News. “They are indirectly asking the U.S. for a compromise plan on nuclear negotiations, now that they are even more equipped than before.”

Shin pointed out that the submarine was revealed just in time for U.S. national security adviser John Bolton’s Seoul visit.

“Kim Jong Un’s investment in large submarines, and even submarine-launched ballistic missiles, must not be underestimated,” Moon Sung-muk, a researcher at the Korea Research Institute for National Strategy, told ABC News. “The pictures disclosed by the North Korean state media aim to show off to both the domestic and international community their naval capabilities.”

Last month, Kim and Trump met in the demilitarized zone in the Korean peninsula for the first time since February's Hanoi Summit ended without an agreement.