As part of efforts to bolster its missile defense against North Korea's threats, South Korea is apparently seeking to combine U.S. technologies with its own, added the source.

"South Korea recently requested additional information on THAAD as well as PAC-III from the Pentagon, including prices and capabilities of the systems," the source told Yonhap News Agency.

The source said the missile defense issue was among major topics in the annual high-level military talks between the allies held in Seoul this month.

It's an open secret that the U.S. hopes for integrated missile defense systems with Japan and South Korea to enhance effectiveness and reduce costs.

U.S. defense officials have emphasized the need for South Korea to beef up its missile defense as Seoul seeks to delay the transfer of operational control (OPCON) from the U.S., slated for 2015. The OPCON transition would make South Korea play a leading role in its national defense, with U.S. Forces Korea shifting to support missions.

Speaking at the National Assembly earlier this week, South Korean Defense Minister Kim Kwan-jin said his military is pursuing "multi-layered" missile defense.

South Korea is in the process of upgrading its current PAC-II units to PAC-III.