A balloon carrying images of North Korean ruling Kim family members is found in Hongcheon, Gangwon Province, Tuesday. It was one of 20 balloons that were flown by a North Korean defectors' group here, Monday night. / Yonhap

By Kang Seung-woo

A North Korean defectors' group floated hundreds of thousands of anti-North Korea leaflets across the border, Monday night, adding fuel to the already-tense situation on the Korean Peninsula.

In response, the police are set to apprehend those who were involved in the campaign that the government believes violates the Inter-Korean Exchange and Cooperation Act

According to Fighters for a Free North Korea (FFNK), it floated 20 balloons carrying 500,000 anti-Pyongyang leaflets across the border from Paju, Gyeonggi Province.

FFNK Chairman Park Sang-hak, said 500 pamphlets depicting the South's success story, 2,000 U.S. one-dollar bills and 1,000 SD cards were also sent to the North, along with the leaflets. Usually, the leaflets criticize the authoritarian regime and urge North Korean people to revolt against their leader Kim Jong-un.

The distribution of leaflets by activists as well as North Korean defectors has long been a major source of tension between the two Koreas as it has led to exchanges of fire in the past. It has taken center stage again recently after Kim Yo-jong, the North Korean leader's sister and probably the second-most powerful person in the country, complained of the leaflet campaigns earlier this month, threatening to cancel a military agreement signed during the inter-Korean summit, April 27, 2018.

Since then, the North's state-run media have slammed the South Korean government's "failure" to stop the "regime-threatening" campaign, and the authorities here have also shown a stern attitude toward the organizers for "causing" inter-Korean tension.

Following the government's pledge to crack down on the leaflet sending campaign, the FFNK secretly flew the balloons unlike in earlier open events.