SEOUL, March 13 (Yonhap) -- South Korea endorsed major defense projects Monday to purchase an additional batch of F-35A stealth fighters and shipborne Standard Missile-6 (SM-6) interceptors, the state arms procurement agency said, in a move to reinforce deterrence against North Korea's evolving military threats.

The Defense Project Promotion Committee approved a 3.75 trillion-won (US$2.85 billion) plan to buy the U.S.-made radar-evading jets through 2028, the Defense Acquisition Program Administration (DAPA) said.

It did not disclose the number of jets to be purchased, but Seoul is expected to bring in some 20 F-35As under the new plan. The country's Air Force currently runs 40 F-35As manufactured by the U.S. defense giant Lockheed Martin.

The jets, if deployed, will prop up the country's Kill Chain preemptive strike system, a pillar of its three-pronged deterrence program against the North's nuclear and missile threats, according to DAPA.

The committee also approved a first-stage purchase plan for the SM-6 manufactured by the U.S. defense firm Raytheon Technologies Corp. It is part of the 770 billion-won two-stage project that will run from this year through 2031 with an aim to better counter threats from hostile aircraft and missiles.

The Navy plans to run the interceptors on its 8,200-ton KDX-III Batch-II Aegis destroyers, which it plans to deploy in the coming years.

The armed service 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.

The committee also gave the green light to a basic plan worth 1.55 trillion won to develop a tactical ground-to-ground vehicle-loaded guided weapon from 2023-2032 to boost the military's precision strike capabilities.

It also approved a 690 billion-won development plan to run from 2023-2030 for local research and production of a ship-to-air missile to be deployed on the Navy's next-generation KDDX destroyers currently under development.