A South Korean navy hydrofoil responds to a distress call on April 15. Seoul's Navy said Tuesday North Korea has been increasing its naval presence along the Northern Limit Line. Photo courtesy of Republic of Korea Navy

SEOUL, Sept. 22 (UPI) -- North Korea has deployed six patrol boats along a disputed maritime border and has been building a fleet of high-speed wave-piercing vessels.

Seoul's Navy said Tuesday during a parliamentary audit before the National Assembly's Defense Committee that North Korea has been increasing its naval presence along the Northern Limit Line on the western coast of the peninsula, South Korean outlet Newsis reported.


"North Korea's military has been increasing the number of naval vessels and bringing in firepower reinforcements," the Navy said in a statement.

According to the Navy's briefing materials, North Korea has been overrunning the NLL as part of its training, censorship and operation-check programs and has installed floats while conducting drills.

The Navy said North Korea is holding exercises to feel out South Korea's military preparedness, but Seoul may not be ready to deal with North Korea's submarine power, including any submarine-launched ballistic missiles, its new torpedo and high-speed stealth surface vessels.

Yonhap reported North Korea has added 10 new high-speed wave-piercing vessels, and a South Korean navy official said the North's fleet is capable of launching torpedoes.

North Korea's Very Slender Vessels can transport its special operations forces to shore and were first detected on South Korean surveillance radar in 2014.

According to Seoul, North Korea has placed three types of VSVs on both sides of the peninsula, and they are painted with radar-absorbent material to disguise the boats from detection. Some of the boats were deployed as tensions escalated between Seoul and Pyongyang in August.

Navy Chief of Staff Jung Ho-seob said North Korea's threats require military cooperation between South Korea and Japan after being asked whether he would approve of Japan's Self-Defense Force participation in the joint drills between the United States and South Korea, but he also added that it was his "personal opinion."