South Korea is awaiting the U.S. government's formal reply to its query about whether South Korean presidents have been a target of its alleged bugging of 35 world leaders, a diplomatic source said Monday.
But many say chances are slim that the Obama administration will provide clear explanations, given the sensitivity of the matter.
Seoul views Washington's reported spying activity on foreign leaders as a "grave issue," the source said on the condition of anonymity.
The U.S. National Security Agency evesdropped on the phone conversations of 35 world leaders, according to a classified document leaked by whistleblower Edward Snowden. It stopped short of revealing their names, although following press reports said German Chancellor Angela Merkel was targeted.
"The South Korean government also takes the issue seriously as it involves spying activities against heads of state, not routine ones," the source said.
Seoul has conveyed its position to Washington through various diplomatic channels, requesting that it check whether the phone conversations of South Korea's presidents were bugged, added the source.
In an initial response, the U.S. said it understands South Korea's concerns, the source said.
The White House said it is reviewing the issue at the instruction of President Barack Obama.
"Today's world is highly interconnected, and the flow of large amounts of data is unprecedented. That's why the President has directed us to review our surveillance capabilities, including when it comes to our closest foreign partners and allies," Caitlin Hayden, spokeswoman for the National Security Council, said in an emailed statement.
Earlier this year, the U.S. intelligence authorities were accused of having spied not only on American citizens and agencies but also foreign diplomatic missions.
A British newspaper, the Guardian, reported earlier this week that South Korea is among 38 "targets" described by the National Security Agency (NSA). They include embassies and missions of the EU, France, Greece and Japan.
The newspaper cited a 2010 document leaked by Snowden. (Yonhap News)