(CNN) North Korea has dropped its long-held demand that the United States withdraw forces from South Korea in exchange for denuclearization, South Korean President Moon Jae-in said Thursday.

The United States has about 28,000 troops stationed in South Korea, a presence that has long irked North Korean leader Kim Jong Un.

However, in the burgeoning spirit of openness and diplomacy, Moon said Kim is willing to give up US troops' removal as a precondition for discussions over denuclearizing the Korean Peninsula.

"North Korea has expressed willingness to give up its nuclear program without making (a) demand that the (US Forces Korea) forces withdraw from the Korean Peninsula," Moon said in a meeting with the press, adding that any proposed troop withdrawal would be a "condition that the US cannot accept."

The South Korean leader, due to meet Kim next week for a historic summit in the Demilitarized Zone, the border separating the two countries, said the North was concerned about its security.