The US Department of State has approved a possible sale to South Korea of Standard Missile-6 (SM-6) shipborne missile interceptors and related equipment to help improve the Asian ally's security capabilities, a government agency said Tuesday.

The Defense Security Cooperation Agency under the Department of Defense made the announcement on the potential government-to-government Foreign Military Sale estimated to cost $650 million.

The South Korean government has made a request to buy up to 38 SM-6 Block I missiles, vertical launch system canisters, training aids and other related equipment, according to DSCA.

"This proposed sale will support the foreign policy goals and national security objectives of the United States by improving the security of a major ally that is a force for political stability and economic progress in the Indo-Pacific region," the agency said in a press release.

"The proposed sale will improve the Republic of Korea's capability to meet current and future threats while further enhancing interoperability with the United States and other allies," it added.

The DSCA delivered the required certification notifying Congress of the possible sale earlier in the day as the sale requires congressional endorsement.

If introduced, SM-6 interceptors are expected to be installed on the South Korean Navy's 8,200-ton Aegis-equipped KDX-III destroyers to be deployed in the coming years.

To counter evolving North Korean missile threats, the South Korean Navy has been operating the SM-2 ship-to-air missiles on its existing fleet of Aegis destroyers, but it has been seeking more advanced, longer-range interceptors.

Manufactured by the US defense firm Raytheon Technologies Corp., the SM-6 is known to have a range of up to 460 kilometers. (Yonhap)