Trash-carrying balloons, launched across the border by North Korea, are seen floating in the sky above Seoul, Oct. 7. Yonhap

North Korea again sent balloons carrying trash toward South Korea on Monday, the military here said, resuming its balloon campaign after about a three-week hiatus.

North Korea floated some 40 balloons in the early hours, with approximately half of them falling in the Seoul metropolitan area and surrounding Gyeonggi Province, the Joint Chiefs of Staff (JCS) said.

The fallen objects were leaflets critical of South Korea and included no hazardous items, it added.

Since late May, North Korea has sent more than 7,000 balloons carrying trash across the border in retaliation against anti-Pyongyang propaganda leaflets sent across the border by activists in the South. Monday's launch marked the 31st such launch.

The JCS condemned North Korea for "crossing the line" with its continued sending of trash-carrying balloons and warned that all responsibility lies within the North.

"Do not further test our military's patience," JCS deputy spokesperson Col. Nam Gi-su said in a statement.

On Sunday, Kim Yo-jong, the powerful sister of North Korean leader Kim Jong-un, claimed that South Korean leaflets had crossed the border into the North the previous day and warned that Seoul would have to pay "a dear price" for such action.

North Korea earlier claimed that South Korean drones carrying anti-North Korea propaganda leaflets were detected over Pyongyang three times in October and threatened to respond with force if such flights occur again. (Yonhap)