North Korea has created ballistic missiles designed specifically to neutralize the US' Terminal High Altitude Area Defense (THAAD) missile system in South Korea, according to the Congressional Research Service.

Pyongyang's latest ballistic missile could be "potentially more difficult to intercept with a missile defense system," the research service noted. "North Korea has demonstrated an ability to launch a salvo attack," launching of missiles without any lag time.

Pyongyang has reportedly developed missiles to cruise at angles that the THAAD could not potentially intercept. Sputnik News noted that the nuclear warheads attached to these ballistic missiles could fly at steeper angles and move at faster speed once they re-enter the Earth's surface, pulling in more gravitational potential energy.

"This is consistent with a possible goal of being able to conduct large ballistic missile attacks with large raid sizes," the report warned.

Meanwhile, the latest satellite images show that North Korea has been ramping up its submarine-launched ballistic missile program (SLBM). A second submersible test-stand barge has allegedly been detected on Pyongyang's west coast in aerial photos taken of the Nampo Naval Shipyard.

According to the analysis written by 38 North, a Korean watchdog site hosted by Johns Hopkins University's US-Korea Institute, the second missile test barge could have several implications on the future of North Korea's SLBM program. It also appears that North Korean leader Kim Jong-un has put a priority on the project.

Barges are usually used by navies to carry out underwater tests of new and modified submarine missile launch tubes and launch systems. They could also be used to conduct an initial missile test launch before such systems are integrated into a submarine. It is not clear if the barge was made in North Korea or bought in from another country.