The US maintains 28,500 troops here under its joint defense treaty with South Korea.

Trump's visit to Camp Humphreys comes in response to a request from the US side, but Cheong Wa Dae officials said the trip may help the new US leader understand South Korea's commitment to the alliance.

The US president has voiced a desire for South Korea to shoulder a greater portion of the cost to maintain US troops here. Seoul insists its contribution must be measured by more than just the cash it pays, noting the construction of Camp Humphreys, which came as part of a base relocation plan, cost it nearly US$10 billion.

Seoul and Washington are expected to begin their defense cost-sharing discussions later in the year or early next year.

The issue will also likely come up at the Moon-Trump summit that will be held later Tuesday at Cheong Wa Dae.

The meeting will mark the third bilateral summit between the two leaders following their meetings in Washington and New York. Their previous encounters also included two three-way talks involving Japanese Prime Minister Shinzo Abe.

The North Korean nuclear issue will sit high on the agenda of the Moon-Trump summit as both countries seek to bring the reclusive North to the dialogue table and discuss its denuclearization.

Pyongyang staged its latest nuclear test on Sept. 3, followed by two ballistic missile tests later that month. It has not staged any provocations since.

The US and South Korean leaders will hold a joint press conference on the outcome of their bilateral talks here.

Moon will later host a state dinner for the US president and his wife that will also likely be attended by dozens of top government officials and business leaders from both countries.

On Wednesday, Trump will visit the country's National Assembly to offer a special speech on the alliance and their joint efforts to counter North Korean provocations. He will be the first US president to make a speech at the South Korean parliament in 25 years, according to Cheong Wa Dae officials.

He will leave for China later Wednesday, when Moon will embark on his own trip to Indonesia.

The two will meet again later in the week when they both attend the Asia-Pacific Economic Cooperation forum in Da Nang, Vietnam on Friday and Saturday. (Yonhap)