President Lee Myung-bak on Tuesday defended his North Korea policy, stressing that inter-Korean relations had undergone a “significant change” despite their frosty appearance.

During his last presidential address to the nation, Lee also said that Pyongyang must realize that by inviting isolation and sanctions from the international community, it was only “drawing closer and closer to a dead-end.”

“The past five years have affirmed for me the fact that in order for North Korea to become a true member of international society and for relations of mutual prosperity to be established, only a foundation built on principles and trust will suffice,” he said at Chunchugwan, the press center of Cheong Wa Dae.

“I did not use the issue of inter-Korean relations as leverage in domestic politics, nor did I provide one-way support unless actual change was observed. I made it clear that provocations would unquestionably be met with proportional responsive measures.”

As the conservative leader prepares to leave office on Feb. 24, observers said the greatest policy challenge for incoming leader Park Geun-hye would be to address the soured relations with the North.

In a departure from his liberal predecessors’ policy of engaging the North with virtually unconditional aid, Lee adopted a reciprocal policy linking Seoul’s economic assistance to the North’s denuclearization.

On top of it, Pyongyang’s fatal provocations in 2010 sent bilateral ties to their lowest ebb in decades. Its third nuclear test on Feb. 12 now poses a daunting policy challenge to the incoming leader.

The outgoing leader also called for consistency in Seoul’s North Korea policy to bring about change in the isolated regime.

“I am confident that the continued and consistent pursuit of principle-based North Korea policies rooted in a solid alliance with the U.S. and cooperation with key nations such as China will secure a new turning point in inter-Korean relations,” he said.

Adding that a wind of “inexorable change” was blowing into the North Korean communities, Lee also urged Seoul to prepare for reunification.

“Though North Korea is rejecting change, the people of North Korea are already changing, and very quickly. Such transformation will not be thwarted, and we will watch it unfold with utmost attention,” he said.

“I firmly believe that the era of reunification is close at hand. We must make haste in our preparations. It goes without saying that a soundly established and airtight national security readiness must provide the basis for that.”

Wrapping up his government’s achievements, Lee stressed that South Korea, which used to be a small country on the periphery in need of outside assistance, has now become a leading player in the world.

Among the achievements, Lee highlighted that the South quickly overcame a set of economic crises; signed free trade agreements with the ASEAN, the EU and the U.S.; and upgraded its national prestige through his Global Korea initiatives.

During his address, Lee also dismissed the criticism that his signature four-river refurbishment project was flawed and caused environmental damage.

Emphasizing that the project should continue, Lee said that it received good evaluations from world organizations such as the Organization for Economic Cooperation and Development and the U.N. Environment Program, and paved the way for a water management project in Thailand.

Lee also expressed “deep regret” over a series of corruption cases that implicated his close aides and associates. Some of them were given his New Year special pardons, which drew sharp public criticism.

“Though I earnestly sought for an administration free of moral fault, I would like to express once more my deep regret that various matters around me caused the Korean people such concern,” he said.

By Song Sang-ho (sshluck@heraldcorp.com)