South Korea vows 'unendurable' response to North's trash balloons

South Korea said on Sunday it would take "unendurable" measures against North Korea for sending trash balloons over the border, which could include blaring propaganda from loudspeakers back at the North.

The announcement from President Yoon Suk Yeol's office followed a meeting by his National Security Council on a response to what Seoul said were more than 700 balloons carrying trash that Pyongyang sent over the heavily fortified border to rile its rival neighbour.

The council condemned the balloons and GPS jamming as an "irrational act of provocation".

Seoul did not rule out resuming the loudspeaker blasts, which it stopped in 2018 after a rare summit with North Korean leader Kim Jong Un, a senior official at Yoon's office told reporters.

The democratic South and the communist North remain technically at war since the 1950-1953 Korean War ended in an armistice rather than a peace treaty.

Seoul is a firm US ally whose sophisticated military regularly holds drills with the US, while Pyongyang is developing missile and nuclear technology that Seoul and Washington say violates UN resolutions.

North Korea has said its balloons were in retaliation for a propaganda campaign by North Korean defectors and activists in South Korea, who regularly send inflatables containing anti-Pyongyang leaflets, food, medicine, money and USB sticks loaded with K-pop music videos and dramas across the border.

The North Korean balloons carrying garbage such as cigarette butts, cloth, paper waste and plastic were found across the capital Seoul from 8:00 pm on Saturday to 1:00 pm on Sunday (1100 GMT on Saturday to 0400 GMT on Sunday), South Korea's Joint Chiefs of Staff said.

It said the military was monitoring the starting point and conducting aerial reconnaissance to track down and collect the balloons, which have large bags of trash suspended beneath them.

South Korean officers with rifles were picking up and bagging what appeared to be trash from the balloons in cordoned-off areas, local media footage showed.

North Korea on Wednesday sent hundreds of balloons carrying trash and what was labelled as manure across the border as what it called "gifts of sincerity". Seoul responded angrily, calling the move base and dangerous.

North Korea has not commented on the weekend balloons.

South Korean Defence Minister Shin Won-sik told US Defense Secretary Austin Lloyd at a conference in Singapore on Sunday that the balloons violated the armistice agreement, according to South Korea's military.

The two reaffirmed a coordinated response to any North Korean threats and provocations based on the South Korea-US alliance's combined defence posture, it said.

Emergency alerts were issued in North Gyeongsang and Gangwon provinces and some parts of Seoul on Sunday, urging people not to come into contact with the balloons and to alert police.