Kim Jong-Un
North Korean leader Kim Jong Un attends the first congress of the country's ruling Workers' Party in 36 years, in PyongyangReuters

North Korean leader Kim Jong-un has reportedly announced a major crackdown on anyone leaking information to rival South Korea and other adversaries. The leader is reported to have vowed that the regime would execute by firing squad anyone involved in anti-state activities.

Multiple sources, cited by Seoul's news agency Yonhap, have confirmed that Kim had set the crackdown in motion in order to squeeze the channels of information leak to South Korea and other nations.

"In the past, those who were caught making phone calls with people outside the country could be set free with some kickbacks. But now, they could be executed, and even their families could be punished," a source was quoted saying.

Kim has been tightening his grip on the isolated nation ever since he took over power following his father's death in 2011. There have been several rounds of executions and purges, including of some high-profile politicians and family members, during Kim's rule.

"I understand that [Kim] has sent a directive to the security agencies and the people, which says he will sternly deal with rebellious impure elements that hand over our internal intelligence to enemies," said another source, who did not wish to be identified fearing reprisal attacks. Since the crackdown was informally announced to the regime's forces, the monitoring of the border regions with China has also increased.

North Koreans are used to making phone calls to their relatives and friends across the border in China and South Korea using illegally smuggled phones into the country. These are also likely to come under the gaze of authorities during the latest crackdown.