South Korean President Park Geun-hye on Tuesday said Seoul will take "stronger and more effective" measures to create an environment that forces change in Pyongyang.
Park, in a speech in parliament, said these measures will make Pyongyang realise that it cannot survive with nuclear development, Xinhua reported.
Her parliamentary speech was arranged to explain Seoul's decision last week to shut down an inter-Korean factory park in North Korea's border city of Kaesong as part of its punitive actions to Pyongyang's nuclear test and long-range rocket launch.
Following its fourth nuclear test -- and its first disputed H-bomb test -- on January 6, North Korea launched a rocket on February 7 to carry an Earth observation satellite into orbit.
Seoul and the international community condemned those provocations as a clear violation of UN Security Council resolutions.
In response to the rocket launch, South Korea decided last Wednesday to stop operations at the Kaesong Industrial Zone, which Seoul saw as a key source of hard currency for Pyongyang to develop nuclear and missile programmes.
North Korea responded last Thursday by shutting down the last symbol of inter-Korean cooperation project, expelling South Korean workers from there and freezing all of South Korean assets in Kaesong, while cutting off the remaining inter-Korean communications hotlines.
Park said the complete shutdown of the Kaesong complex represented only the start of a series of sanctions toward North Korea in cooperation with the international society.
It will not happen any more like in the past that South Korea yields to North Korea's provocations and provide unconditional aid to it, Park said.
