奥巴马将在柏林演讲，推动世界无核化

U.S. President Barack Obama is set to lay out his vision for advancing toward a world free of nuclear weapons during a speech Wednesday at the historic Brandenburg Gate in Berlin.

Hours before the planned address, Mr. Obama met with German Chancellor Angela Merkel for talks that covered, among other things, U.S. Internet surveillance. 

In a joint news conference afterwards, Mrs. Merkel said that while "enemies and opponents" can use the Internet to threaten democracy, she had stressed to the U.S president that there should be "balance and proportionality" between the need to monitor threats and to preserve a "liberal order."

Mr. Obama, for his part, called the U.S. Internet surveillance program "circumscribed" and "narrow," insisting that U.S. intelligence agencies are not "rifling through ordinary emails" of "German citizens or American citizens or anyone else" and that the Internet and telephone surveillance programs are under federal court supervision.

He said his administration has struck "the appropriate balance" between protecting the American people and preserving "civil liberty and privacy." He also reiterated that the surveillance programs have "saved lives."