"We have put a great team together for our talks with North Korea", Trump said in a Twitter post yesterday. South Korea's Defense Ministry said Tuesday there have been no discussions yet between Washington and Seoul on modifying the drills, which usually take place in August.
USA officials have talked about a comprehensive one-shot deal in which North Korea eliminates its nukes first and receives rewards later.
Multiple media agencies reported seeing Kim Yong Chol, a former military intelligence chief and current vice chairman of North Korea's ruling party, at the Beijing airport.
Announcing the lower-level talks held yesterday, US State Department spokeswoman Heather Nauert said: "We continue to prepare for a meeting between the president and North Korean leader Kim Jong-un".
South Korean President Moon Jae-in could also be going to Singapore next month for a three-way summit with his USA and North Korean counterparts, a government official in Seoul said on Monday.
American officials are skeptical that North Korea will ever entirely abandon its nuclear weapons, and South Korean President Moon Jae-in said North Korea isn't convinced it can trust security guarantees from the US.
It wasn't immediately clear whether the American officials including Sung Kim, the USA ambassador to Manila, were heading to the border village between the two Koreas, where they met with North Korean officials on Sunday.
Subsequently, U.S. and North Korean officials on Sunday began preliminary talks at the Korean border to set the agenda for the summit.
Analysts believe the United States is trying to determine whether North Korea is willing to agree to sufficient steps toward denuclearisation to allow a summit to take place.
Sanders also cited Trump's cancellation letter as a reason that "the North Koreans have been engaging" about a renewed summit.
Summit diplomacy seems to be heating up.as North Korea's former intel chief is in New York City for talks with the U.S. Secretary of State.
USA and North Korean officials have been continuing preparations for the possible summit.
They discussed their shared goal of achieving "the complete and permanent dismantlement of North Korea's nuclear, chemical, and biological weapons and ballistic missile programs".
But events have moved quickly since Kim Jong Un made a conciliatory New Year's address at the end of last year, following months of sharply rising tension.
If it occurs, the Trump-Kim summit will be the first between U.S. and North Korean leaders after nearly 70 years of enmity and confrontation since the start of the 1950-1953 Korean War and more than a quarter century of failed negotiations.
The Moon and Trump administrations very much want the meeting, he said, "and Kim says he wants a summit, so it's going to happen".
Due to sanctions against him, Kim Yong Chol is banned from visiting the United States.
He has been at Kim Jong-un's side in both of his meetings this year with Chinese President Xi Jinping.
Trump's tweet offered praise for the longtime USA adversary, and the latest signal that his concerns about the North's stance toward the summit have been allayed. That impromptu session was aimed at salvaging the summit that Trump had said he was scuppering just two days earlier.
Kim reported from Seoul, South Korea.
North Korea, which refers to its nuclear weapons program as its "treasured sword" keeping the country safe, has repeatedly said it is not interested in unilateral disarmament.
North Korea, in return, would demand the U.S. normalize its relations with it, ease sanctions against it and remove it from a list of state sponsors of terrorism, which could immediately help the North's economy.
Following an unusually provocative 2017 in which Kim's engineers tested a purported thermonuclear warhead and three long-range missiles theoretically capable of striking mainland USA cities, the North Korean leader has engaged in a flurry of diplomatic activity in recent months.
The general is a notorious figure in South Korea, where he is accused of masterminding the 2010 sinking of the Cheonan navy corvette, which killed 46 sailors, an attack for which North Korea denies responsibility.