For more than 70 years, balloons have played a role along the border dividing North and South Korea.
Starting in the Korean War, governments on both sides dropped leaflets by way of balloons.
Balloons headed north have also carried various other items over the years — from computer flash drives to medicine and food.
One of the more bizarre balloon payloads was carried to North Korea in 2014 when South Korean activists launched about 10,000 "Choco Pies" over the border.
The chocolate-covered cake and marshmallow snack was a popular perk for North Koreans who worked in South Korean factories in the Kaesong Industrial area.
That experimental manufacturing zone in North Korea was an effort to improve relations between the two countries that lasted for about a decade, until North Korea shut it down in 2013.
More recently, the use of cross-border balloons was deflated by a controversial South Korean law passed in 2020.
The Seoul government banned leafletting across the border — a move it said was aimed at improving cross-border relations.
South Korea's Yonhap news agency reported that the military was tracking a balloon that crossed the border from the North on Monday, although it said government officials believe it was just a weather balloon.
