WASHINGTON (Yonhap) ― The U.S. government has approved a possible sale to South Korea of PAC-3 interceptor missiles and related equipment for an estimated cost of $1.405 billion, a U.S. defense agency said.

The State Department has approved South Korea’s request that 136 PAC-3 missiles be sold to the Asian ally, the Defense Security Cooperation Agency said in a statement.

The agency said it delivered the required certification notifying Congress of the sale Wednesday.

The estimated cost is $1.405 billion, it said.

“This proposed sale will contribute to the foreign policy and national security objectives of the United States by meeting the legitimate security and defense needs of an ally and partner nation,” the agency said.

South Korea “is one of the major political and economic powers in East Asia and the Western Pacific, and a key partner of the United States in ensuring peace and stability in that region,” it said. “It is vital to U.S. national interests to assist our Korean ally in developing and maintaining a strong and ready self-defense capability.”

South Korea is seeking to buy PAC-3 interceptors to upgrade its present PAC-2 air defense system by 2020 to better defend against threats from North Korea. PAC-3 missiles are also a key part of Seoul’s plan to build the Korean Air and Missile Defense system.

“This sale will increase interoperability between the ROK’s ground and sea-based (Aegis) ballistic missile defense forces and U.S. Forces Korea, which not only affects ROK national security but also the security of the U.S. personnel assigned in the ROK,” the DSCA said. ROK stands for Republic of Korea, the country’s official name.

“This sale will provide the ROK with the capability to defeat lower tier Ballistic Missile Defense threats and will decrease the ROK’s reliance on the deployment of U.S. combat forces to maintain stability in the region,” it said.

The proposed sale of this equipment and support will not alter the basic military balance in the region, the agency said. The principal contractors will be Raytheon Corporation in Andover, Massachusetts, and Lockheed Martin Missiles and Fire Control in Dallas, Texas, it said.