SEOUL, Jan. 19 -- South Korean President Park Geun-hye on Tuesday expressed worry about sending a wrong signal to the Democratic People's Republic of Korea (DPRK) unless strong UN sanctions are imposed on Pyongyang over its fourth nuclear test.

Park told a cabinet meeting that if strong and effective measures are not drawn up, it would give a wrong signal to the DPRK that the international society can do nothing over Pyongyang's fifth and sixth nuclear tests.

The president urged officials to make diplomatic efforts to draw up strong and comprehensive sanctions from the UN Security Council by closely cooperating with allies.

Tensions rose on the Korean Peninsula after the DPRK claimed on Jan. 6 that it tested its first hydrogen bomb.

South Korea resumed blaring propaganda messages from loudspeakers across the border into the DPRK, which in turn, restarted its own propaganda broadcasts in response.

Pyongyang scattered more than 1 million copies of anti-South Korea leaflets through air balloons in part of Seoul and some of the northern region close to the inter-Korean border.

Park said the military should maintain solid defense readiness over the DPRK's possible provocations, noting that the military should immediately retaliate against any DPRK provocations.

She instructed the military to make a thorough preparation for possible cyber attack from the DPRK.

A large amount of emails impersonating the South Korean presidential office and the foreign ministry had been reportedly sent to Seoul government officials to poll opinions about the DPRK's fourth nuclear test.

The impersonated emails were believed to have been sent from Pyongyang to conduct a cyber attack. The South Korean policy had launched an investigation.