President Joe Biden is spending his Saturday working to strengthen ties with South Korea’s new leader, Yoon Suk Yeol, as the two sides consult on how to best counter North Korea’s nuclear threat at a time when real diplomacy seems unlikely.

Following World War II, the Korean peninsula was divided into two separate countries. In a democracy, Biden is touring factories for computer chips and next-generation automobiles in South Korea, where he is also holding talks for increased cooperation. However, in the north, a deadly coronavirus outbreak has broken out in a largely unvaccinated autocracy that can best command the world’s attention by flexing its nuclear weapons.

White House national security adviser Jake Sullivan told reporters aboard Air Force One as Biden arrived in South Korea that the US has coordinated with Seoul and Tokyo on how to respond if the North conducts a nuclear test or missile strike while Biden is in the region or soon after. Sullivan spoke with his Chinese counterpart Yang Jiechi earlier this week, urging Beijing to use its clout to persuade North Korea to stop testing.

According to Sullivan, “China should consider taking whatever steps it can to reduce the possibility of a provocative” act.

Biden is spending his Saturday in Asia as part of a five-day trip, focusing on his relationship with Yoon, who took office just over a week ago. One mission will be to reassure South Korea about the United States’ commitment to confronting North Korean leader Kim Jong Un.

Seoul is concerned that Washington is reverting to the Obama administration’s “strategic patience” policy of ignoring North Korea until it demonstrates seriousness about denuclearization, which was criticised for ignoring the North while it built up its nuclear arsenal.

North Korea has turned down South Korean and US offers of help with its COVID-19 outbreak, lowering hopes that such cooperation could help ease nuclear tensions or even lead to talks. According to senior Biden administration officials who briefed reporters, Biden and Yoon are expected to discuss ways to work with the international community to get much-needed vaccines and tests to the North.

The US president began his visit on Saturday by laying a wreath at Seoul National Cemetery and burning incense while wearing white gloves and a solemn expression. Biden will meet privately with Yoon later, hold a joint press conference, and attend a state dinner at Korea’s National Museum.

One focus will undoubtedly be a menacing but economically vulnerable North. Both leaders, however, are keen to highlight their growing trade relationship, which is being bolstered by the opening of major plants in the United States by two Korean industrial giants, Samsung and Hyundai.

Biden faces mounting domestic opposition as inflation approaches a 40-year high, but his administration sees one clear economic victory in the competition with China. For the first time since 1976, Bloomberg Economics Analysis predicts that the US economy will grow faster than China this year, a prediction that White House press secretary Karine Jean-Pierre attributed to Biden’s spending on coronavirus relief and infrastructure, which resulted in faster job growth.

The invasion of Ukraine by Russia has sparked broader discussions between the two countries, and the war has resulted in an unprecedented set of sanctions imposed by the US and its allies.

South Korea has joined the United States in imposing export restrictions on Russia and blocking Russian banks from using the SWIFT payment system. Its involvement was crucial in preventing Russia from gaining access to computer chips and other technologies required for weapons and economic development.

Many White House officials believed that Kim’s nuclear ambitions would prove to be the administration’s most difficult challenge, and that the North Korean leader would try to put Biden to the test early on in his presidency.

Pyongyang held off on missile tests for the first 14 months of Biden’s presidency, despite the administration’s efforts to reach out through back channels in the hopes of restarting talks that could lead to the North’s denuclearization in exchange for sanctions relief.

The silence, however, did not last. North Korea has conducted 16 missile tests this year, including its first flight of an intercontinental ballistic missile since 2017 in March, demonstrating a potential range that includes the entire United States.

The Biden administration is urging China to stop North Korea from testing missiles or nuclear weapons. Sullivan said on Air Force One that Biden and Chinese President Xi Jinping could talk over the phone in the coming weeks.

Biden has slammed Beijing’s human rights record, trade practises, military harassment of Taiwan’s self-ruled island, and other issues. While Biden has stated that China is the US’s greatest economic and national security competitor, he believes it is critical to maintain open lines of communication so that the two countries can work together on issues of mutual concern. North Korea is probably at the top of the list.

Biden will not visit the Demilitarized Zone dividing the Korean peninsula during his visit, according to White House officials, which has become standard for presidents visiting Seoul since Ronald Reagan. Vice President Joe Biden visited the DMZ in 2013. The president’s decision to skip the stop this time, according to Sullivan, was not motivated by security concerns.

Biden will instead visit the Combat Operations Floor of the Air Operations Center on Osan Air Base, south of Seoul, on Sunday. It is considered by the US to be one of the most important installations in Northeast Asia.