U.S. considers 'proportional' response to Sony hacking attack

By David Brunnstrom and Jim Finkle WASHINGTON (Reuters) - The United States said on Thursday a cyber attack on Sony Pictures was a serious national security matter and the Obama administration was considering a proportional response, although the White House stopped short of blaming North Korea. U.S. government sources said on Wednesday that investigators had determined the attack was "state sponsored" and that North Korea was the government involved. A U.S. government official said on