South Korean police are investigating six U.S. nationals who allegedly tried to send plastic bottles filled with one-dollar bills, rice and USBs loaded with the Bible to North Korea, as the Lee Jae-myung administration cracks down on border activities that it views as exacerbating inter-Korean tensions.

The Incheon Ganghwa Police Station confirmed on Monday that the American men, aged in their 20s to 50s, were taken into custody on June 27 on Gangwha Island near the border. They have been released, and the Incheon Metropolitan Police are now carrying out a full-scale probe.