South Korean President Yoon Suk-yeol warned that North Korea will pay for “reckless” military aggression against the ROK on Friday, in an emotional speech marking a national mourning day for soldiers who died in past inter-Korean battles.

Yoon’s remarks for West Sea Defense Day followed the conclusion of large-scale U.S.-ROK Freedom Shield exercises on Thursday, and came as the allies are set to conduct a variety of follow-up drills in the coming weeks and months.

“I will make sure that North Korea pays for its reckless provocations,” Yoon said, referring to North Korea’s sinking of the ROKS Cheonan in March