South Korea’s defense minister visited a core military unit for addressing North Korean missile threats on Monday, a rare move that underlined concerns about Pyongyang’s launch of its longest-range missile in more than four years the previous day.

Suh Wook made the visit to the ROK Army Missile Command to review military preparedness in the wake of the DPRK’s barrage of missile tests in January, the defense ministry said in a press release, emphasizing the command’s “central” role in responding to launches.