US President Joe Biden and South Korea's newly sworn-in President Yoon Suk-yeol held a meeting on Saturday in Seoul, during which they said they will consider stepping up joint military drills in response to the North Korean "threat".

Biden noted that any possible meeting with the leader of North Korea "would depend on whether he was sincere."

After Biden's first trip as President to Asia, the two leaders stated that "considering the evolving threat posed by" North Korea, they "agree to initiate discussions to expand the scope and scale of combined military exercises and training on and around the Korean peninsula."

Elsewhere in their statement, the two leaders expressed "concern over the recent Covid-19 outbreak" there and claimed they "are willing to work with the international community to provide assistance" to the country to help fight the virus.

Yoon claimed the offer has nothing to do with "political and military issues."

However, the US and South Korea are committed to North Korea's "complete denuclearization", Yoon said, adding that "nothing is more important than a strong deterrence against the North."

Closed-door talks were held with Yoon ahead of a joint press conference and state dinner.

North Korea's coming step will help steer the US-South Korean relationship under Yoon, former CIA analyst Soo Kim told AFP.

"Should Kim proceed with a test during Biden's visit, he will effectively be helping the two countries find greater justification to work together on the North Korea issue," she said.

Biden will be visiting another key US ally, Japan, on Sunday.

According to a US official, in addition to tensions over North Korea and the US-led draconian campaign on Russia over the war in Ukraine, Biden's priority on Saturday was to win Yoon and establish "a strong personal relationship" with him, although he has not completed two weeks into his presidency.

South Korea is seen, just like Japan, as a chief player in US strategy to stand in the face of a rising China and secure what Washington calls the "free and open Indo-Pacific."

The US official, who preferred to remain unnamed, told reporters that the US President's trip to Asia "is about demonstrating unity and resolve and strengthening the coordination between our closest allies".

However, the visit is overshadowed by what the official named "sabre-rattling" across the fortified border in North Korea, which the White House alleges might test either a nuclear-capable missile or explosive to benefit from the high-profile moment.

Cutting-edge investments 

Yoon accompanied Biden on a tour, on Friday, to a Samsung semiconductor factory, where the US President highlighted the Samsung plant's role in maintaining the semiconductors' fragile global supply chain.

He said the chips are an essential component in almost every piece of sophisticated modern technology, and the US and South Korea should work to "keep our supply chains resilient, reliable and secure."

For the US President, snarled supply chains are a critical domestic political challenge, with Americans greatly frustrated due to the rising prices and setbacks after the Covid pandemic recovery.

On Monday, Biden will unveil the Indo-Pacific Economic Framework for Prosperity, which is a big new US initiative for regional trade. He will later join a regional summit of the Quad -- a grouping of India, Australia, Japan, and the United States.