North Korea puts military on alert to attack U.S. targets

North Korea said it put its artillery and missile units on the highest alert on Tuesday, ordering them to be prepared to attack South Korea and U.S. military installations in Hawaii and Guam.

North Korea's People's Army Supreme Command said its strategic rockets and long-range artillery units were assigned to strike U.S. bases on the nation's mainland, in addition to bases in Hawaii, Guam and other operational zones in the Pacific. The threat came hours after South Korean President Park Guen-hye warned North Korea that it would only survive if it abandoned its nuclear weapons, long-range missiles, threats and provocations, the New York Times reports.

"They should be mindful that everything will be reduced to ashes and flames the moment the first attack is unleashed," the North Korean command said, according to the New York Times.

Tensions have continued to grow after North Korea launched its third nuclear test in February. After the test, Washington and Seoul pushed for a United Nations Security Council resolution to impose additional sanctions on North Korea.

"I strongly urge North Korea to change," Park said, according to the New York Times. "North Korea must immediately abandon its thought that nuclear weapons will protect its regime."

On Tuesday, three websites run by North Korean defectors and anti-Pyongyang activists reported hacking activities that interrupted or stopped their operations. The attacks came a week after synchronized virus attacks paralyzed the computer networks of three banks and three broadcasters in South Korea. Officials said they are investigating the possibility of North Korean involvement, the New York Times reports.