South Korea's Yonhap News Agency said on Saturday that North Korea had stopped broadcasting a radio station that was "sending encrypted messages to its agents" in the neighboring south, in the latest indication that Pyongyang is changing its approach to Seoul.

North Korea has intensified pressure on its southern neighbor in recent weeks, declaring it "the main enemy," saying that "the North will never unite with the South," and pledging to enhance its capability to carry out a "nuclear strike against the United States and its allies in the Pacific region," according to Reuters.

Pyongyang's radio, known as the numbers station, had been broadcasting mysterious encrypted numbers believed to target North Korean spies operating in South Korea, and its website was also down on Saturday.

North Korean leader Kim Jong-un ordered in a speech during his ruling party's year-end meeting a "decisive change in policy" in relations with the South. Early on Saturday, North Korea announced plans to dissolve organizations responsible for civilian exchanges with South Korea.

The Korean Central News Agency referred to a decision "to reorganize all related organizations."

North Korea and South Korea are still technically at war, as the Korean War that took place between 1950 and 1953 ended with a truce, not a peace treaty, and tensions are escalating between the two countries.