The South Korean military is apparently seeking to upgrade its missile defense capability to Patriot Advanced Capability (PAC)-III, with the purchase of Terminal High Altitude Area Defense (THAAD) systems in mind as a possible next step, a U.S. defense industry official said Wednesday.

If confirmed, it would contradict South Korean Defense Minister Kim Kwan-jin's statement that his country is just pushing for the so-called low-tier Korea Missile Defense (KAD) system.

South Korea is reportedly under pressure to play a bigger role in the U.S. initiative to beef up its regional missile defense posture.

South Korea bought 48 used PAC-IIs from Germany in 2007, but skepticism has persisted over its capability to thwart North Korea's ballistic missiles, which might be tipped with chemical or nuclear warheads.

In the first step to improve its missile defense networks, the South Korean military plans for an upgrade to PAC-III systems, according to Michael Trotsky, vice president of air and missile defense systems at Lockheed Martin.

"After the PAC-III system upgrade, what their defense command is looking for is what is the next longer-range air and missile defense system that could protect against longer-range ballistic missiles and in particular and work with the Patriot system that Korea already has," he told Yonhap News Agency.

He added South Korea is "very interested in taking a look at the THAAD system" produced by Lockheed, although it's still in the very initial stages of mulling over various potential systems.

Trotsky said Lockheed may be bracing for competition with Israel's air defense system and some others for the supply of South Korea's next-stage work to sharpen its missile defense.

"So, Lockheed Martin is obviously going to help them get all of the data on the THAAD system that they need to make their decision," he said.

THAAD is designed to shoot down short, medium, and intermediate ballistic missiles in their terminal phase using a hit-to-kill method.

When North Korea's missile threats peaked in the spring, the Pentagon announced the deployment of a THAAD system to Guam in what it called a precautionary move.

On Tuesday, the Pentagon also announced that it has successfully conducted a complex missile defense flight test using THAAD weapon systems in the western Pacific.

Industry sources said it's urgent for South Korea to replace its current PAC-IIs, which are mainly intended to counter air-breathing targets such as jets, helicopters and fixed-wing aircraft.

They estimate modifying South Korea's PAC-II systems to PAC-III would cost millions of dollars.

The Lockheed official said the price tag on the PAC-IIIs would depend on the amount of purchase and its timing.

The Pentagon gave no answer to Yonhap's inquiry over its consultations with South Korea on missile defense. (Yonhap News)