The Yonhap News Agency in Seoul reports that South Korea is working with its allies to develop ballistic missiles with a range of up to 500 miles. The agency reported that "multiple" sources suggested a deal with the United States was imminent.
U.S. State Department spokeswoman Victoria Nuland said that, while talks over bilateral security arrangements are ongoing, there isn't "anything new to report."
Yonhap reports that its direct questions over missile defense went unanswered by the White House. The report adds that South Korean President Lee Myung-bak may be stumping on missile defense ahead of presidential polls in December.
Lee is ineligible for re-election but is campaigning on behalf of his ruling Saenuri Party.
Tensions on the Korean Peninsula escalated last year following the death of North Korean leader Kim Jong Il. Various analysts have suggested Pyongyang this year may be preparing for a nuclear test.
South Korean forces fired warning shots on North Korean boats that crossed a maritime border last week. North Korea doesn't recognize the de facto border and authorities from Seoul said they hadn't seen signs of provocation from Pyongyang.