By Jim Acosta and Kevin Liptak, CNN

Honolulu, Hawaii (CNN)—The United States is hitting North Korea with a new set of economic sanctions after determining the country was behind last month's computer hack at Sony.

The White House said a new executive order targets leaders in North Korea's government, preventing them from accessing property and entering the United States. The isolated nuclear regime, which has denied involvement in the Sony hack, was already subject to a strict set of U.S. economic restrictions.

The Federal Bureau of Investigation has maintained North Korea was behind the broad computer breach at Sony, despite evidence that some technology experts said points instead to former employees of the studio. On Friday officials said the new set of sanctions was further indication of their confidence in North Korea's culpability, and said that private tech firms aren't privy to the intelligence proving Pyongyang's guilt.

President Barack Obama signed the executive order putting the new sanctions in place on the second-to-last day of his winter vacation in Hawaii. Before his vacation began in mid-December Obama said North Korea was responsible for the attack and the United States was preparing a response. The White House said Friday's announcement reflected the beginning of that response.

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