"The policy persistently pursued by the U.S. to stifle (North Korea), groundlessly stirring up bad blood towards it would only harden its will and resolution," a statement attributed to North Korea's Foreign Ministry said.

On Friday, the United States hit North Korea with the new sanctions after the FBI said North Korea 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 FBI has maintained North Korea was behind the broad computer breach at Sony, though some technology experts say others could be involved -- such as 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.

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.

"The order is not targeted at the people of North Korea, but rather is aimed at the government of North Korea and its activities that threaten the United States and others," Obama wrote in a letter to House Speaker John Boehner.

The country poses a "continuing threat to the national security, foreign policy and economy of the United States," Obama wrote.

Among the agencies targeted by the new sanctions Friday was the Reconnaissance General Bureau, an intelligence agency the United States said was responsible for "major cyberoperations" in North Korea.

The new sanctions also target officials at North Korea's Mining Development Trading Corporation, which the United States says is responsible for the country's arms dealing and weapons export business.

Seven officials who represent North Korea's arms dealing trade in Africa, Iran, Russia and Syria were designated by the U.S. Treasury as subject to the new economic sanctions.

(CNN)