The U.S. THAAD system is a powerful anti-missile tool, but wouldn't be effective in defending against a North Korean nuclear attack coming as part of a barrage of conventional warheads, a U.S. analyst said Monday.

Garth McLennan, who has closely followed American foreign and security policy, made the point in an article contributed to the website 38 North, forecasting that THAAD's deployment to South Korea would lead to the North stepping up its production of ballistic missiles.

South Korea already has formidable missile defense capabilities, including a large arsenal of Patriot-2 short-range missiles set to be upgraded to PAC-3s, but the addition of THAAD, which is designed to defend against short and intermediate-range missiles, would provide South Korea with a more layered defensive posture, he said.

"THAAD would not, however, serve as an effective tool in countering a North Korean nuclear strike if such an attack were haystacked among a barrage of conventional warheads," he said. "The THAAD system is a powerful anti-missile tool ... but in this case, it would not serve as a bulletproof measure against a North Korean nuclear attack."

The nuclear warheads would be the proverbial needles in the haystack of conventional munitions.

Currently, such a defensive system does not exist, he said.

"If THAAD were deployed to the Korean peninsula, it would hardly be a stretch for Pyongyang to immediately and aggressively increase their production of ballistic missiles and their assorted delivery systems. THAAD, for all it can do, has limits that can be overcome by high volume missile stockpiles and SLBM capabilities," McLennan said.

SLBM stands for submarine-launched ballistic missiles.

Following the North's long-range missile test in February, Seoul and Washington launched official talks about placing a Terminal High Altitude Area Defense battery in the South to bolster defense against missile threats from the communist nation.

Sources have said that the THAAD talks have moved forward to a point where the two sides are now looking into candidate sites for deployment, including not only existing U.S. military bases, but also mountainous areas away from cities.

McLennan said that South Korea's capability to counter a "saturation-based ballistic missile attack" from the North is limited, with the doctrine attached to missile interception calling for a two-to-one ratio for every missile fired, he said.

"If Pyongyang were to launch a haystacked barrage, it would almost immediately tax Seoul's capacity to repel it. At the same time, nuclear-armed ballistic missiles would almost certainly confront the ROK with the problem of leakage in any attempt to intercept them," he said. (Yonhap)