The Korean Central News Agency said Friday that North Korea's adversaries were mounting cyberattacks on the country at the same time joint South Korean-U.S. military exercises began in the region.
"They are seriously mistaken if they think they can quell North Korea's voices of justice through such base acts," South Korean news agency Yonhap quoted the state-run KCNA as saying.
North Korea said this week it viewed annual U.S.-South Korean operations Foal Eagle and Key Resolve as a threat.
Yonhap reports that access to the Internet in North Korea was blocked for about 24 hours starting Wednesday. The attack allegedly targeted state-run news outlets.
North Korea this week pulled out of the armistice agreement that halted the Korean War in the 1950s. Martin Nesirky, a spokesman for U.N. Secretary-General Ban Ki-moon, said the terms of the 1953 agreement don't allow for one side to back out unilaterally.
The U.N. Security Council last week censured North Korea for its February underground nuclear test, which Pyongyang said was part its campaign against the United States.