Since the announcement of the deployment of the Terminal High Altitude Area Defense system here, the talk of town has been its possible hazardous effects on the health of those living near the deployment site.

The efficacy and capacity of the advanced missile defense system have also been topics of debate, with pundits, military officials and the public discussing what THAAD can and cannot do.

THAAD is designed to target ballistic missiles at higher altitudes in their terminal stages, most likely fired from the hostile North Korea. South Korean military said that the missile batteries can strike objects that are up to 200 kilometers in front of the system and/or 100 kilometers behind it.

When its radar detects an incoming threat, the target is identified and engaged. Then an interceptor is fired from a truck-mounted launcher and uses kinetic energy to destroy the incoming missile at between 40 to 150 kilometers in altitude.

Theoretically, it could cover the U.S. military bases in Pyeongtaek, Gyeonggi Province, which sits 170 kilometers from the THAAD’s expected base of Seongju-gun, North Gyeongsang Province. It would not be able to intercept high-altitude missiles targeting Seoul, where 10 million people reside.

But whether THAAD can protect the Pyeongtaek area has been disputed by experts.

Jang Young-geun, a professor of aerospace and mechanic engineering at Korea Aerospace University, recently revealed a simulation showing that THAAD would not be able to intercept a ballistic missile fired from near Mount Baekdusan adjacent to the North Korea-China border to Pyeongtaek.

He explained that the missile detection and firing would take approximately 203 seconds, by which time the missile would be under the altitude of 40 kilometers.

Activist Jung Wook-sik, who co-authored a book on military defense with Rep. Kim Jong-dae of the minor opposition Justice Party, said that the actual range of THAAD’s interception might be shorter than 200 kilometers -- estimating it would be around 150 kilometers -- considering the maximum interception range would be shorter in relation to the altitude,

Apart from the missile batteries, the radar for THAAD is another contentious issue.

The Lockheed Martin-developed weapon system uses X-band AN/TPY-2 radars developed by Raytheon.

The radar can be deployed in two different modes depending on the needs of warfare: the forward-based mode provides a wider range of detection to acquire ballistic missiles in the boost -- or ascending phase -- of flight. The terminal mode detects the weapons in their terminal -- or descending -- phase.

The latter is estimated to have a range of 600 kilometers, which would put North Korea's northern territory at range. But the former is expected to be able to cover up to 2,000 kilometers, putting China under range.

China has been fiercely protesting the THAAD deployment, raising concerns that the U.S. weapon -- which would be operated by the USFK -- would put it under Washington’s surveillance.

The South Korean Defense Ministry, who has maintained that THAAD is exclusively against North Korean threats, countered by saying that the radars would only be operated in the terminal mode.

A military official at a base that operates the Green Pine radars pointed out that the AN/TPY-2 typically covers a relatively smaller area at a higher accuracy.

“How can a radar that is about the size of a soccer goalpost cover the massive land of China? It’s absurd,” he said, asking not to be identified.

Compared to Green Pine that can easily shift positions, the AN/TPY-2 for THAAD is conventionally in a fixed position. As the radars would be pointed toward North Korea, officials said this would make surveillance of China -- whose territory is mostly west of South Korea -- nearly impossible.

But some have speculated that the allies may bring in multiple THAAD systems.

During the parliamentary questioning, Rep. Kim Sung-chan suggested that two or three more THAAD systems should be deployed here, to which Defense Minister Han Min-koo agreed.

The existence of more than one THAAD system means both terminal and forward-based modes could potentially be operated.

Another limitation of THAAD, which the Defense Ministry has already admitted to, is that it would be useless in defending Seoul and the surrounding capital region, even if it was installed near the area. The Scud short-range ballistic missile launchers are mostly based near the capital, and the SRBMs typically fly at altitudes beneath the THAAD’s interception range.

Despite its limits, experts say that THAAD is likely to significantly boost missile defense in South Korea. It currently has the Patriot missile system with PAC-2 batteries, which are slated to be upgraded to PAC-3 starting late this year.

The missiles are said to be effective in defending against lower-altitude ballistic missiles, which the Seoul government described as adding to “multi-layered defense.”

While the system will provide an upgrade to missile defense, pundits question whether it will be overwhelmed by Pyongyang’s large missile inventory.

Michael Elleman and Michael J. Zagurek Jr. of the North Korea analysis website 38 North wrote that a single THAAD battery holds limited interceptors ranging from 48 to 96.

Given that the North has hundreds of Scud missiles, they pointed out that mounting defense against the large number of incoming missiles will be difficult in terms of actual interception and radar detection.

As the AN/TPY-2 radars are pointed toward the North, there will also be challenges in defending against submarine-launched ballistic missiles, they pointed out.

By Yoon Min-sik (minsikyoon@heraldcorp.com)