Korean war of words - and music - grows louder

North Korea appears to have increased efforts to drown out South Korean anti-Pyongyang broadcasts, with a spate of messages being broadcast from inside the isolated country's border Monday.

Seoul, however, said the transmissions were too weak to be heard in the south.

In response to the North's claimed hydrogen test last week, the South has been blaring a diverse playlist from high-decibel loudspeakers placed at the border -- featuring everything from K-pop to criticisms of Pyongyang's human rights record.

But it seems North Korea is trying to match Seoul's propaganda campaign.

"The North initially operated its own loudspeakers at two locations and has now expanded to several locations," a South Korean government source was quoted as saying by local news agency Yonhap.

"In fact, the anti-South loudspeaker broadcasts appear to be coming from every location where we are broadcasting."

Another official reportedly said that the sound coming from North Korea was "very weak," but analysts had previously noted that Pyongyang's primary concern would be to nullify the impact of South Korea's messages north of the border.

Such is the importance of ideology in the reclusive North that the previous round of inter-Korean psychological warfare pressured Pyongyang into last August's landmark cooperation deal -- albeit not before an exchange of fire.

So far the North Korean regime has been defiant in defending its recent nuclear test as a defensive measure in the face of the South's alliance with the United States.

The North's state-run state-run Korean Central News Agency carried a statement from leader Kim Jong-un for a second successive morning Monday, also a day after an American B-52 bomber flew over the peninsula.

It said that Kim had posed for photos with nuclear scientists and technicians involved in the latest test and praised them for “having glorified” his two predecessors -- late father, Kim Jong-Il, and grandfather, Kim Il-Sung.

Kim made known his expectation that the country will continue to "make uninterrupted advances" in its nuclear development, despite the theoretical limitations set by multiple United Nations Security Council resolutions.

South Korea continued to remain vigilant as Joint Chiefs of Staff Chairman General Lee Sun-jin warned during an inspection that the North is likely to launch further sudden provocations.

Meanwhile, the South's unification ministry announced that it would restrict to a minimum the number of its citizens at the inter-Korean Kaesong Industrial Complex.

124 South Korean companies operate just north of the border at the complex, which was shut down for several months in 2013 during a period of high tensions.

The new restriction was "aimed at securing the safety of South Koreans as the North is expected to react to Seoul's resumption of anti-North Korean loudspeaker broadcasts," ministry spokesperson Jeong Joon-hee told reporters.

Meanwhile, South Korea's foreign ministry revealed Monday that Seoul would be involved in meetings this week with the U.S., Japan and China to discuss another U.N. Security Council resolution.

Six-party talks aimed at denuclearizing North Korea -- also involving Russia -- broke down after being last held in 2008.

Seoul's current envoy to the talks is to meet his Washington and Tokyo counterparts Wednesday, before moving on to China for dialogue with Beijing's representative the following day.

A date with Moscow was yet to be decided.