An old-fashioned style of Korean pop music called trot is South Korea's most powerful psychological weapon against North Korea.

Most songs the military has broadcast to North Korean soldiers across the military demarcation line over tannoys along the DMZ were trot (pronounced "teuroteu" and short for "foxtrot").

They stopped in June 2004, but on May 24 this year, after the North sank the Navy corvette Cheonan, the military started airing propaganda programs on FM radio frequencies beamed across the border.

On Wednesday, the Defense Ministry submitted a list of the most frequently broadcast songs to lawmaker Song Young-sun of the Future Hope Alliance. Songs by Na Hoon-a, a big-time trot star in the 1960s and 70s, were broadcast most frequently during the 1980s. Many of the jaunty tunes were still at the top of the list in the 1990s and 2000s.

The FM radio programs targeting North Korean soldiers are broadcasting a playlist of 184 songs that North Korean residents would like, many among them sung by new-generation trot singers such as Jang Yoon-jung and Park Hyun-bin.

"Pop music can be a powerful psychological weapon targeting the oppressed in the North," Song said. "We should immediately resume tannoy broadcasts in response to the North's recent provocations."