SEOUL -- Republic of Korea (ROK) and the Democratic People's Republic of Korea (DPRK) have expanded their respective propaganda broadcasts across the border after Pyongyang's rocket launch on Sunday, ROK's Yonhap news agency reported on Wednesday citing a military official.

Seoul's military deployed mobile loudspeakers, mounted upon trucks, in frontline units right after Pyongyang's launch of a rocket to deliver an observation satellite into orbit.

In protest against the launch, ROK strengthened psychological warfare in addition to fixed loudspeakers, which Seoul resumed blasting at 11 locations along the border following the DPRK's fourth nuclear test on Jan. 6.

In response, the DPRK forces also added mobile loudspeakers to border areas after having restarted the broadcasting of propaganda messages across the border from fixed speakers.

The ROK military has extended the broadcasting time to more than six hours per day, while blasting the messages in an irregular and intermittent way.

More exchange in border areas of psychological warfare escalated the already heightened tensions on the Korean peninsula.

Seoul, Washington and other countries agreed to adopt tougher new sanctions against Pyongyang over the recent provocations, as well as separate bilateral and multilateral restrictions toward the DPRK.

The DPRK is banned under UN Security Council resolutions from testing a rocket by use of ballistic missile technology and from staging a nuclear test.