Cha, senior adviser and Korea Chair at CSIS, was commenting on North Korean leader Kim Jong-un's reported willingness to give up his nuclear weapons program in exchange for security guarantees. Kim delivered the message during a meeting with South Korean President Moon Jae-in's top national security adviser Monday.

"North Korea's diplomatic overtures must be viewed in the context of its overall byungjin strategy -- which sees national strategic objectives as defined by the development of nuclear weapons and economic development, not a tradeoff of one for the other," Cha wrote. "Thus, Pyongyang's overtures may not represent a watershed change in strategy, but a tactical shift, building on the platform of nuclear weapons to seek economic benefits from the outside world."

Cha, who served on the National Security Council under George W. Bush, said the US and South Korea should prioritize coordination of policy.

"South Korea has said that progress in inter-Korean talks would operate on the principle of 'parallel progress' with US-(North Korea) talks on denuclearization." he said. "Yet, South Korea has already announced a summit (with North Korea) in April without any visible commitment yet by the United States to talks."

US President Donald Trump reportedly wanted Cha as his first ambassador to Seoul but withdrew the nomination after he voiced objections to the administration's considerations of a limited military strike on the North. (Yonhap)