Story highlights North Korea is facing daily "intensive and persistent virus attacks," state news reports

It blames "the U.S. and the South Korean puppet regime" for such cyberattacks

North Korea has bristled under international pressure since its third nuclear test

North Korea's state news agency reported Friday that the country's Internet servers are subject to daily "intensive and persistent virus attacks" that the government blames on "hostile forces" including the United States.

"It is nobody's secret that the U.S. and the South Korean puppet regime are massively bolstering up cyberforces in a bid to intensify the subversive activities and sabotages against the DPRK," according to the official KCNA report.

"... They are seriously mistaken if they think they can quell the DPRK's voices of justice through such base acts. The U.S. and its allies should be held wholly accountable for the ensuing consequences."

North Korea has been under intense international pressure since its third nuclear test earlier this year, which spurred the U.N. Security Council to approve tough new sanctions.

Pyongyang threatened a possible "pre-emptive nuclear attack" earlier this month, and the official news agency reeled off agreements with South Korea that it said would no longer apply. Among them are its non-agression pacts with the South, which helped bring the Korean War to a close in 1953.

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Experts on the region and U.S. officials said the recent frenzy of ominous language from North Korea under its leader Kim Jong Un makes the situation on the Korean Peninsula more worrying and unpredictable.

On Tuesday, U.S. Director of National Intelligence James Clapper testified to Congress that North Korea's development of a nuclear weapons program poses a "serious threat."

While calling the developments "disturbing," KCNA's report Friday did not specify what damage -- if any -- the alleged cyberattacks had done in North Korea. It promised that Pyongyang "will never remain a passive onlooker," though it didn't indicate what the country might do about any cyberattack.

U.S. Army Gen. James Thurman, commander of U.S. Forces Korea, said last spring that North Korea had its own "growing cyberwarfare capability." In a statement before a congressional hearing, he said such attacks "have been increasingly employed against a variety of targets, including military, governmental, educations, and commercial institutions."