South Korea's military is moving quickly to improve its defense systems after North Korea vowed to continue its nuclear armament as a self-proclaimed nuclear weapons state, the government said Monday.

North Korean leader Kim Jong-un made it clear during a rare gathering of the ruling Workers' Party over the weekend that he will stick to his signature "byeongjin" policy, which calls for developing the country's nuclear weapons and economy in tandem.

He also said his country, as a "responsible nuclear weapons state," would not use nuclear arms first unless its sovereignty is threatened.

South Korea, in response to a series of provocations, has been in the process of developing a set of missile detection and defense systems, known as the Kill Chain and the Korean Air and Missile Defense (KAMD), with the aim of putting them into service in the mid-2020s.

Amid the North's evolving threats, Seoul plans to put these systems at the top of its defense spending priorities.

The Kill Chain and the KAMD also form part of Seoul and Washington's 4D Operational Concept that seeks to detect, disrupt, destroy and defend against potential nuclear and missile attacks from the North.

"South Korea and the U.S. will draw up the details of the 4D Operational Concept during the Korea-U.S. Integrated Defense Dialogue (KIDD) meeting in Washington, D.C.," a government official said on the condition of anonymity.

The two daylong bilateral talks are scheduled to open in Washington later in the day. The official said the meeting will cover ways to create implementation programs for the operational plan.

Under the Kill Chain system, South Korea plans to improve its surveillance of North Korean military facilities by deploying unmanned aerial vehicles, such as the Global Hawk and the F-35A fighter jets, starting in 2018.

To improve its strike capabilities on North Korean nuclear and missile sites, the South Korean military also plans to deploy the German-made Taurus air-to-surface missiles in the second half of the year.

The Taurus has a range of more than 500 kilometers, making it capable of striking nearly all parts of North Korea from the central regions of South Korea. (Yonhap)