South Korean President Moon Jae-in and North Korean leader Kim Jong Un agreed to make several steps toward denuclearization to promote "a land of peace" after their summit in Pyongyang, North Korea, on Wednesday.

The agreement included commitments to the "permanent dismantlement" of North Korea's primary nuclear facility in Yongbyon and the allowing of international inspectors to observe the disassembly of an engine test site.

Moon prefaced this plan by noting the US needed to reciprocate the measure, though it was unclear what he had in mind.

Kim and Moon also agreed to collaborate on a bid to host the 2032 Summer Olympics. Additionally, Kim said he "promised" to visit the South Korean capital, Seoul, "in the near future."

South Korean President Moon Jae-in and North Korean leader Kim Jong Un agreed to make several steps toward denuclearization to promote "a land of peace" after their summit in Pyongyang on Wednesday.

Kim and Moon signed a document called the September Pyongyang Joint Declaration, which offered more specifics than previous agreements had, in front of a gaggle of news reporters at their third summit meeting. Moon arrived Wednesday as the first South Korean president to visit Pyongyang in 11 years.

The agreement included commitments to the "permanent dismantlement" of North Korea's primary nuclear facility in Yongbyon and to allowing international inspectors to observe the closing of an engine test site and missile launch pad. Moon prefaced this plan by noting the US needed to reciprocate the measure, though it was unclear what specifically he had in mind.

"We have agreed to make the Korean Peninsula a land of peace that is free from nuclear weapons and nuclear threat," Kim said. "The road to our future will not always be smooth, and we may face challenges and trials we can't anticipate."

Kim and Moon also agreed to make a joint bid to host the 2032 Summer Olympics. The two countries competed together during the 2018 Winter Olympics in Pyeongchang, South Korea, despite some protests from conservative South Korean lawmakers and athletes. The move was part of an initial effort to improve relations between the two Koreas ahead of a summit between the US and North Korea, which took place in June.

Kim also said he "promised" to visit the South Korean capital of Seoul "in the near future." Moon said a visit might take place this year "unless there are certain special circumstances." A visit by a North Korean leader to Seoul, something that hasn't happened since the Korean Peninsula was divided, would most likely spark mass protests, as took place when North Korea's delegation of athletes and musical performers visited the country during the Winter Olympics.

Kim Jong Il, Kim Jong Un's father who then led North Korea, made a similar promise to visit Seoul after a summit in 2000, but the trip never happened.

While the two leaders expressed cautious optimism for the months ahead, the US, a key South Korean ally, expressed concern over the developments. US-North Korean diplomatic relations have seemingly stalled after Secretary of State Mike Pompeo suddenly canceled a planned trip to North Korea in August.

President Donald Trump embraced Kim after meeting with him in Singapore in June. Conversely, Trump has publicly sought to drive a wedge between China and the North, at times accusing China of slowing the diplomatic process.

Republican Sen. Lindsey Graham of South Carolina, a skeptic of North Korea's recent outreach to the international community, said he was "concerned" over Moon's visit to Pyongyang.

Graham said in a tweet Tuesday that he feared Kim's visit to South Korea would undermine the US's "maximum pressure" strategy aimed at influencing North Korea.

"While North Korea has stopped testing missiles and nuclear devices, they have NOT moved toward denuclearization," Graham said, adding, "South Korea should not be played by Kim Jong Un."

Following the declaration's signing, however, Trump praised the development and called it "very exciting."

"Kim Jong Un has agreed to allow Nuclear inspections, subject to final negotiations, and to permanently dismantle a test site and launch pad in the presence of international experts," Trump said in a tweet on Tuesday night. "In the meantime there will be no Rocket or Nuclear testing."