President Moon Jae-in is expected to be briefed personally by the U.S. secretary of state, who landed at Osan Air Base.
Last year, about 50,000 South Korean and 17,500 US troops participated in Ulchi-Freedom Guardian, billed as the world's largest command-and-control exercise and aimed at defending against a North Korean attack.
Another thing about the process that has supposedly started: We've seen North Korea start a process before, with previous administrations, only to break agreements, deceptively continuing its nuclear program.
It has nearly 30,000 troops in South Korea and the two countries hold annual large-scale drills.
"Sanctions played a big role, but they'll come off at that point, I hope it's going to be soon", he said, adding he looked forward to taking them off. There are still few details about Trump's decision to suspend USA "war games" in South Korea, which could fuel discussion about a weakening of the alliance.
The administration's argument is that the incremental approach used by past administrations has allowed North Korea to extract rewards and incentives from the USA, only to ultimately renege and refuse to give up its nukes. There are also joint US-Japanese drills each year. His focus on diplomacy, including earlier meetings with the leaders of China and South Korea, is a sharp contrast with his rapid-fire testing of long-range missiles and the fiery exchanges of threats and insults past year that created real fears of a war on the divided peninsula.
Mr Pompeo arrived at Osan Air Base south of Seoul from Singapore early on Wednesday evening and met for close to an hour with General Vincent Brooks, commander of US Forces Korea, at the air base before heading by motorcade to Seoul.
China has confirmed that Pompeo will visit Beijing on Thursday.
Interestingly, the North made no secret of China's behind-the-scenes presence at the summit.
But with no clear signs of how or when the process will unfold, others have been more cautious about the summit's implications.
Pompeo was in Seoul on Wednesday to brief South Korean officials on the summit.
"A lot has been made of the fact that the word "verifiable" didn't appear in the agreement", Pompeo said of the hoint statement.
However, dismantling Pyongyang's nuclear weapons programme will present a daunting challenge.
As Trump acknowledged that denuclearization would not be accomplished overnight, the North suggested Wednesday that Trump had moved away from his demand for complete denuclearization before USA sanctions on the long-isolated country are removed.
The International Atomic Energy Agency (IAEA) has said it is ready to verify a deal, although it focuses on monitoring nuclear materials and sites rather than disarmament. North Korea blamed botulism and ingestion of a sleeping pill and dismissed torture claims.
A slight majority of Americans believes that President TrumpDonald John TrumpWhat you need to know about Tuesday's elections Danny Tarkanian wins Nevada GOP congressional primary Laxalt, Sisolak to face off in Nevada governor's race MORE has handled North Korea well, according to a Reuters/Ipsos poll released Wednesday.