WASHINGTON - North Korea experienced sweeping and progressively worse Internet outages extending into Monday, with one computer expert saying the country's online access is "totally down."

The White House and the State Department declined to say whether the U.S. government was responsible.

President Obama said Friday that the U.S. government expected to respond to the hacking of Sony Pictures Entertainment Inc., which he described as an expensive act of "cyber vandalism" that he blamed on North Korea.

Obama did not say how the United States might respond, and it was not immediately clear whether the Internet connectivity problems represented the retribution. The U.S. government regards its offensive cyber operations as highly classified.

"We aren't going to discuss, you know, publicly operational details about the possible response options or comment on those kind of reports in anyway except to say that as we implement our responses, some will be seen, some may not be seen," State Department spokeswoman Marie Harf said.

North Korea has forcefully denied it was responsible for hacking into Sony. But the country has for months condemned the film The Interview, a Sony satirical comedy about a plot to assassinate the North Korean leader. Sony canceled plans to release the movie after a group of hackers made terroristic threats against theaters that planned to show it.

North Korean diplomat Kim Song, asked Monday about the Internet attack, told the Associated Press: "I have no information."

Ivan Simonovic, the U.N. assistant secretary-general for human rights, told reporters he didn't want to speculate about the nature of the Internet outages but said he hoped it would be "thoroughly investigated."

Doug Madory, the director of Internet analysis at Dyn Research, an Internet performance company, said Monday the problems began over the weekend and grew progressively worse to the point that "North Korea's totally down."