WASHINGTON -- US Secretary of State Mike Pompeo said Monday that President Donald Trump's willingness to meet with the North Korean leader is a reflection of US commitment to diplomacy.

Trump is set to meet with Kim Jong-un in Singapore June 12 after threatening last year to "totally destroy" the regime over its nuclear weapons and ballistic missile tests.

"Our willingness to meet with Kim Jong-un underscores the Trump administration's commitment to diplomacy to help solve the greatest challenges, even with our staunchest adversaries," Pompeo said in a speech at the Heritage Foundation think tank that mainly focused on laying out conditions for a new nuclear deal with Iran.

"But that willingness has been accompanied by a painful pressure campaign that reflects our commitment to resolve this challenge forever," he said, referring to US-led sanctions on North Korea.

Trump surprised even his aides when he accepted Kim's invitation to a summit in March. The two leaders are expected to discuss ways to dismantle the North's nuclear weapons program, but Pyongyang threatened to pull out of the meeting last week, citing US demands for "unilateral" denuclearization.(Yonhap)