A former presidential chief of staff has attributed currently strained inter-Korean relations to North Korea's failure to correctly understand and accept the so-called "sunshine" engagement policy pursued by previous liberal South Korean governments.

Yu Woo-ik, President Lee Myung-bak's first chief of staff, said in a special lecture in Russia that the engagement policy itself is not to blame. He suggested that the problem is how it is being interpreted by the North.

According to Yu, the president is ready to employ flexible policies toward North Korea and negotiate in all areas unless Pyongyang attempts to jeopardize the principles behind the creation of a nuclear-free Korean Peninsula.