US President Donald Trump has arrived in South Korea where he's expected to meet with President Xi Jinping to seal a trade war truce.

The two leaders are expected to hold talks on Thursday, their first meeting since Trump began his second term.

"I think we're going to have a great meeting with President Xi of China, and a lot of problems are going to be solved," Trump told reporters on Air Force One heading from Japan.

"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."

Trump said he expects to reduce US tariffs on Chinese goods in exchange for Beijing's commitment to curb exports of fentanyl precursor chemicals.

“They’ll be doing what they can do,” he said.

Negotiators from the world's top two economies hashed out a framework on Sunday for a deal to pause steeper American tariffs and Chinese rare earths export controls, according to US officials.

After arriving in the southern city of Busan on Wednesday, Trump strolled down a red carpet and shook hands with officials. He then boarded his helicopter, heading for Gyeongju.

Trump is due to meet with South Korean President Lee Jae Myung and address a summit of CEOs.

Lee's office said the pair will discuss trade, investment and peace on the Korean peninsula.

Hours before Trump's arrival, North Korea announced it had test launched sea-to-surface cruise missiles off its western coast in a show of strength against Pyongyang's "enemies".

Trump has extended an invitation to North Korean leader Kim Jong Un to meet while he is on the peninsula, but on Air Force One he said his focus was on the Xi meeting.

"At some point, we'll be involved with North Korea. I think they'd like to, and I'd like to," the US president said.

Trump and Kim last met in 2019.

Regional leaders will gather in Gyeongyu for this year's Asia-Pacific Economic Cooperation summit. (Agencies)