North Korea fired suspected artillery shots two days in a row earlier this week, a South Korean military source confirmed Wednesday.

The South Korean military detected one trajectory presumed to be a North Korean artillery piece being launched toward the western seas on Monday morning, the source -- who requested to remain anonymous -- said.

The official declined to share further details, including the exact location and time of the launch, for security reasons.

The belated confirmation came days after South Korea’s Joint Chiefs of Staff Sunday announced that North Korea had fired two projectiles believed to be artillery rounds between 6:21 and 6:37 p.m. that day.

North Korea reportedly fired unguided artillery shells -- whose calibers are estimated to be less than 240 millimeters in diameter -- from conventional multiple-rocket launcher systems for the two days.

Monday’s artillery firing marked the sixth round of saber-rattling since the inauguration of South Korea’s President Yoon Suk-yeol on May 10.

Under the Yoon government, North Korea has launched artillery shells three times, including the firing of five artillery pieces of 240 mm calibers toward seas to the west on June 12, which came a day after the defense ministerial meeting of South Korea, the United States and Japan.

The South Korean military has been assessing North Korea’s intent to launch artillery shots for two days. The artillery launches could be part of the North Korean military’s summer training that kicked off this month, or they could be a show of force in the run-up to the South Korea-US combined aerial exercises.

The United States Air Force’s F-35 stealth fighter jets have been deployed on the Korean Peninsula since July 5 for the first time in around five years to conduct drills with the South Korean Air Force.

Sunday’s artillery firing also came on the day when Philip Goldberg, the new US ambassador to South Korea, arrived in South Korea to start his term.

The South Korean military generally does not inform the public of North Korea firing unguided artillery shells whose calibers are under 300 millimeters. For instance, the KN-25 short-range ballistic missile launched from 600 mm super large-caliber guided rocket launchers and artillery fired from the KN-09 300 mm multiple rocket launchers with a range of 200 km are exceptions.

But the recent confirmation comes at the request of local media outlets that came across leaked information.

The South Korean military will no longer announce or confirm North Korea’s artillery drills -- which are frequently conducted on the front lines -- in the future, The Korea Herald learned. 

The policy has been determined mainly due to concerns that public announcements on the matter could disclose intelligence, surveillance and reconnaissance capabilities to North Korea and have adverse impacts on the South Korean military’s readiness posture.