North Korea must make concrete pledges toward curbing its nuclear weapons program, such as dismantling its main nuclear complex and allowing international inspections to confirm the process, when leader Kim Jong Un meets U.S. President Donald Trump as soon as next month, South Korea's foreign minister said.

Kang Kyung-wha said in an interview at the World Economic Forum in Davos that she is optimistic North Korea will agree to concrete steps toward abandoning its nuclear weapons and ballistic missile programs, developed in violation of United Nations resolutions.

"The (North Korean) leader has promised to his people many times that 'I'm going to take this country toward economic development.' He has to deliver that, and he's not going to get the kind of significant assistance unless he takes concrete steps toward denuclearization and somehow eases the sanctions regime," she said on Thursday.