BEIJING >> With a dose of mystery and the flair of a showman, North Korea’s young leader, Kim Jong Un, used his debut as an international statesman on Wednesday to present himself as confident, reasonable — and willing to bargain.

Kim’s surprise two-day visit to Beijing, his first known trip abroad since taking power, was effectively a reminder of how much he has set the agenda in the crisis over his nation’s nuclear arsenal — and of what a strong hand he has going into talks, first with President Moon Jae-in of South Korea next month and later with President Donald Trump.

Kim has yet to say what concessions he is willing to make, or what he may demand from the United States in return. But he continued to dominate the diplomatic process, reaffirming his willingness to meet with Trump and repeating his vague commitment to the denuclearization of the Korean Peninsula in talks with President Xi Jinping of China, according to Xinhua, the Chinese state news agency.

During Trump’s first year in office, Kim raced ahead with breakthrough tests of a hydrogen bomb and missiles capable of hitting the U.S. mainland. Then he abruptly changed course and used the Winter Olympics to seize the initiative, surprising the world with a rapprochement with the South and then an offer to meet with Trump.

Through it all, the Trump administration has been largely relegated to reacting and catching up to Kim. And so it was again this week, when Kim suddenly showed up in China on an armored train and was shown beaming next to Xi, whose cooperation has been critical to Trump’s strategy of “maximum pressure” on the North. The state media in China and North Korea announced the meeting on Wednesday, after two days of secrecy.

In images and in words, Kim and Xi signaled that they had repaired the relationship between their countries, which had soured as Kim had accelerated his nuclear program and Xi had responded by endorsing — and enforcing — more punishing sanctions proposed by the United States.

“The friendship between North Korea and China that was personally created and nurtured together by former generations of leaders from both our sides is unshakable,” Kim told Xi, according to Xinhua. Xi went out of his way to recall the warm friendship between his father, a high-ranking Communist Party official from the Mao era, and Kim’s father, Kim Jong Il, the North’s previous leader.

It is too soon to say whether the meeting marks a softening of China’s posture toward Kim Jong Un or of its commitment to international sanctions against North Korea. But the visit served to highlight Beijing’s unique leverage over North Korea, even as Trump is threatening China with a trade war.

Trump can talk about maintaining “maximum pressure” on the North, but ultimately China — the North’s main trade partner — still decides what that means, because it can choose how strictly to enforce sanctions.

“China is saying to the United States and the rest of the world: Anyone who wants a deal on anything on the future of the Korean Peninsula, and certainly something which deals with nukes, don’t think you can walk around us, guys,” Kevin Rudd, a former Australian prime minister who is on good terms with the Chinese leadership, said in Hong Kong on Wednesday.

The Chinese government said it had briefed the White House on Kim’s visit, adding that Xi had sent a personal message to Trump. On Wednesday morning, Trump expressed optimism on Twitter about the potential for diplomatic success, saying there was “a good chance” that Kim would “do what is right for his people and for humanity.”

But there was little in the public accounts of Xi’s discussions with Kim to support such a positive assessment. Though Xinhua quoted Kim as saying he was open to talks with Trump and committed to denuclearization, North Korea’s own state media made no mention of either.

Xinhua also quoted Kim as proposing “phased, synchronized measures” by South Korea and the United States — a phrase that suggests a desire to negotiate a gradual drawdown of his arsenal, but which also echoes the North’s position in past talks that dragged on and ultimately failed. One major difference between then and now is that North Korea has a far more advanced nuclear arsenal.

Trump’s incoming national security adviser, John R. Bolton, meanwhile, has expressed little patience for extended negotiations. He has said that North Korea should be asked to park its nuclear arsenal at the Oak Ridge nuclear facility in Tennessee.

If China decides to soften its stance on sanctions and act as North Korea’s protector, Kim will enter the talks with Trump in a considerably stronger position than he otherwise would have.

“It is very unlikely that Kim Jong Un consulted with the Chinese before offering to meet Trump,” said Sergey Radchenko, a professor of international relations at Cardiff University in Wales. “This in itself was a rebellious affront to the Chinese leadership. But by doing this, Kim immeasurably strengthened his negotiating position vis-à-vis the Chinese. He came to Beijing not as a supplicant but as an equal.”

Many analysts said they believed China had initiated the visit, essentially telling Kim that he could no longer afford to be cavalier about his bigger, richer neighbor, and telegraphing to Trump that America could pay heavily for keeping China on the outside.

Beneath the new bonhomie in the official accounts of Kim’s trip, the edgy nature of the seven-decade-old China-North Korea relationship was still apparent.

No agreements between the two leaders were announced, even on basic issues. Xi, in his public comments, made no reference to Kim’s expected meeting with Trump, an omission that may have reflected Xi’s displeasure at being left on the sidelines.

There was also no public comment in Beijing about what Kim was planning to offer Trump or what role China would play as the talks approached, questions that are of the utmost importance to China.

While China supports the international effort to rid North Korea of its nuclear weapons, it has also been careful not to press the North hard enough to risk a collapse of the Kim regime, which could potentially lead to a united Korean Peninsula, under a U.S. security umbrella, on China’s border.

“China needs to know North Korea’s calculations,” said Da Wei, a professor at the University of International Relations in Beijing. “Kim knows the negotiations cannot fully succeed without China’s support. China’s involvement will make any solution more viable.”

Some analysts said Kim was repeating a pattern set by his father, who visited China shortly before his 2000 summit meeting with South Korea’s then-president, Kim Dae-jung. Kim Jong Il was then about six years into his tenure as North Korea’s leader, just as his son is now.

“Now six years into his own reign, Kim III seeks to play the role of the proactive, peace-seeking statesman,” said Lee Sung-yoon of the Fletcher School of Law and Diplomacy at Tufts University.

He may hope to get Trump to settle for “another faulty, open-ended, non-biting nuclear deal” that would make it “politically near-impossible for the U.S. to talk about, let alone implement, a pre-emptive strike, John Bolton at the head of the National Security Council notwithstanding,” Lee said.