North Korea sent another batch of balloons carrying filth and propaganda to South Korea over the weekend, prompting a stern reaction from the South Korean government, which vowed Sunday to take “unendurable” action.

“Dispatching of trash balloons and jamming GPS are despicable and irrational acts of provocation that could not have been imagined by a normal country,” National Security Adviser Chang Ho-jin said after presiding over a National Security Council meeting called in response.

“We will take measures that will be unendurable for North Korea following today's meeting,” the NSA adviser added, warning against any further provocations, which he said were aimed at causing anxiety and confusion in the South.

A senior source from the presidential office did not elaborate what consequences North Korea would face, but that it would not rule out resuming anti-North Korea loudspeaker broadcasts along the border.

North Korea began to launch the trash-filled balloons from around 8 p.m. Saturday, some 720 of which were detected in and around Seoul and regions farther south such as the Chungcheong provinces as of Sunday afternoon, according to South Korea’s Joint Chiefs of Staff.

At around 8:45 p.m. Saturday, an alert was issued across Seoul and regions close to the border warning residents to refrain from outdoor activities and report sightings of suspicious objects to authorities.

Over in Singapore, South Korea’s Minister of National Defense Shin Won-sik and the United States Secretary of Defense Lloyd Austin jointly condemned North Korea’s actions as they met for bilateral talks on the last day of the Shangri-La Dialogue.

South Korea and the US defense chiefs agreed that North Korea’s balloon campaign violated the Armistice Agreement that halted the Korean War, according to the Seoul’s Defense Ministry.

The two defense chiefs in particular called out North Korea’s recent attempt to launch another military reconnaissance satellite as being in violation of the United Nations Security Council resolutions, the Seoul ministry said.

Following the failed satellite launch attempt late Monday last week, North Korea has staged a series of provocations beginning with the trash balloons that were sent Tuesday and Wednesday before flying them again Saturday.

The estimated number of North Korean balloons that landed in South Korea in the past week stands at about 1,000, according to the latest count by the South’s JCS.

The balloons contained objects such as trash, excrement and propaganda leaflets, and did not appear to have caused direct harm to safety, the JCS said. The fallen balloons are being collected for further analysis.

North Korea tried to jam navigation or GPS signals in South Korea’s northwestern region for the fifth consecutive day on Sunday. Sunday’s GPS jamming attack that began from around 11 a.m. did not result in any meaningful disruptions, the South Korean JCS said.

Besides the balloon launches and GPS jamming, North Korea fired several short-range ballistic missiles toward the sea east of the Korean Peninsula on Thursday.