His remarks came as South Korea is facing deepening diplomatic woes with Japan over a recently-erected statue of a girl that symbolizes its wartime sexual slavery.

Japan is demanding the removal of the statue installed before its consulate here, saying that it is a violation of the 2015 deal reached to resolve their long-standing rift over the victims of Japan's sexual slavery during World War II. In protest, Tokyo recalled in its ambassador, who has yet to come back to Seoul.

With public sentiment in South Korea worsening over the diplomatic spat, some key presidential candidates are calling for renegotiations on or even withdrawal from the agreement. 

This comes in addition to South Korea's friction with China over the South Korea and US plan to install an advanced missile defense system called THAAD. 

The two allies say that its deployment in South Korea is necessary to better counter North Korea's growing threat, but Beijing claims it will hurt its strategic security interest.

Cha made clear that the two agreements that South Korea reached with Japan and the US on each front are "quite important." 

Meanwhile, with regard to the North's nuclear threat, the expert said that the issue will surely be one of the major challenges confronting the Donald Trump administration, especially in its early term.

"I think until the president is in place and his team conducts a policy review, we can't really have a guess as to what policy would be," he said. "The only thing I could say is that North Korea will be one of the early challenges for the new administration and I think they will be taking that very seriously." (Yonhap)