US President Donald Trump landed in South Korea on Wednesday for the final part of his Asia trip, expressing optimism over reaching a trade war truce with Chinese President Xi Jinping after summit talks with South Korean President Lee Jae Myung.

Trump left Tokyo for South Korea just hours after North Korea test-fired a nuclear-capable cruise missile. The US president is set to address a summit of CEOs and meet with Lee in Gyeongju on Wednesday.

South Korea's presidential office said it would welcome Trump with a replica gold crown and award him with the "Grand Order of Mugunghwa," the country's highest decoration.

Are relations between the US and China improving?

The unresolved trade situations loom large over Trump's visit.

Trump said a trade deal with South Korea would be "finalized very soon," speaking to delegates at the APEC CEO summit in the South Korean city of Gyeongju.

"We're really wedded, and we have a very special relationship, a special bond. In fact, we're working with you on shipbuilding," the US president added.

Meanwhile, he is expected to meet with Xi in South Korea on Thursday.

Speaking to reporters aboard Air Force One en route to Gyeongju, Trump seemed unperturbed by the North Korea missile test and said he was focused on his meeting with Xi.

"The relationship with China is very good. So I think we're going to have a very good outcome for our country and for the world, actually," the US president said.

Trump said he expected a "lot of problems" to be solved with Xi in their talks.

The US president said he expected their first face-to-face talks of his second term to result in Washington lowering tariffs imposed on Beijing in relation to fentanyl.

Trump also said he was "not sure" whether he would discuss the sensitive topic of self-ruling Taiwan during his meeting with the Chinese leader.

Trump said Monday that the United States and China are close to a trade deal after weekend talks at the ASEAN summit in Malaysia.

China won't rule out force over Taiwan ambitions

But China was not going to shy away from the topic.

Peng Qing'en, a spokesperson for China's Taiwan Affairs Office, told a news conference in Beijing that peaceful "reunification" under the "one country, two systems" model is the fundamental approach to "resolving the Taiwan issue."

"We are willing to create ample space for peaceful reunification and will spare no effort to pursue this prospect with the utmost sincerity," he said. "However, we absolutely will not renounce the use of force and reserve the option to take all necessary measures."

Elsewhere, Trump has talked up a possible meeting with North Korean leader Kim Jong Un, including during this trip, but there has been no comment on the matter from Pyongyang.

Kim has previously said he could be open to talking if the United States stops urging him to give up nuclear weapons.

Edited by: Dmytro Hubenko