By Alex Jensen

SEOUL

‘Let Us Just Love’ was one of the hopeful messages to blare from powerful South Korean loudspeakers as Seoul's border propaganda continued Saturday, with the aim of reaching ordinary North Koreans even several kilometers from their tense border.

The track by K-pop group A-Pink was on a playlist apparently aimed at demonstrating the South's prosperity in contrast to notorious conditions in the reclusive North.

Pyongyang's first official response to Seoul's latest such campaign was to warn Friday that a physical conflict could break out -- on a peninsula stuck in a state of uneasy truce since the 1950-53 Korean War.

South Korea's high-decibel broadcasts played out at nearly a dozen places along the border, risking the wrath of a neighbor that has repeatedly shown a willingness in recent years to open fire.

For now North Korea's only noticeable move has been to start playing its own propaganda soundtrack, according to the South's military.

It is a familiar story that led to a landmark cooperation deal last August, demonstrating the authoritarian North's vulnerability to any threat to its own ideology.

But this time Pyongyang has the world to answer to after claiming Wednesday to have conducted its first hydrogen bomb test.

North Korea also released footage Friday of its latest submarine-launched ballistic missile exercise, as if to tell the world that its nuclear threat is closer than many doubting analysts have suspected in the last few days.

A South Korean military official did, however, suggest Saturday that the video was not entirely genuine.

"It is believed that North Korea's SLBM ejection test video has been edited with images from a Scud missile ejection film made in the past," the official was quoted as saying by local news agency Yonhap.