US President Donald Trump has departed South Korea after concluding his whistle-stop tour of east Asia, without achieving one of his key stated goals — a face-to-face meeting with North Korean leader Kim Jong Un.

On Wednesday, Trump claimed the encounter had not materialized due to "timing" problems.

During talks with South Korean President Lee Jae-myung at the Gyeongju National Museum, Trump expressed concern that "North Korea's nuclear development is significantly threatening the security of the Korean Peninsula and northeast Asia."

But Trump also left the door open to dialogue with Pyongyang, claiming he still has a "good relationship" with Kim and was ready to return to meet the North Korean leader "at any time."

Experts, however, point out that the global geopolitical situation has changed dramatically since the two leaders met in Singapore,  Hanoiand at the Demilitarized Zone (DMZ) between North and South Korea during Trump's first term in office, and that Kim has since cultivated a close military and trade relationship with Russia.

'Kim has new, powerful friends'

Despite Trump stating repeatedly before arriving in South Korea that he hoped to be able to meet Kim, Choo Jae-woo, a professor of foreign policy at Kyung Hee University in Seoul, says a face-to-face between the two leaders was more than unlikely.

"It was never going to happen," Choo told DW. "The rules of the game have changed, and while I would not go as far as to say that this was a snub to the president, Kim certainly has other new and powerful friends that he can call on."

Those friendships were spelled out in no uncertain terms in the days leading up to Trump's arrival in the region, as Russian President Vladimir Putin greeted North Korean Foreign Minister Choe Son-hui in Moscow on Monday. The Russian leader was filmed asking Choe to "send his regards" to Kim, adding that, "the development of our relationship… is progressing smoothly."

Earlier in the day, Choe had held talks with Foreign Minister Sergey Lavrov, during which she said North Korea-Russia relations had been "elevated to a new level" and that Pyongyang was committed to supporting Russian national sovereignty and territorial security.

On Wednesday, North Korea announced that it had test-fired a volley of sea-to-surface strategic cruise missiles at targets in the Yellow Sea. The North Korean military claimed the weapons were capable of carrying nuclear warheads.

Last week, ahead of Trump's visit to the region, Pyongyang carried out a ballistic missile test, the first of its kind since Lee Jae-myung took office in June.

As a final indication of where North Korea sees its future, North Korean state media reported that a high-ranking delegation of Russian economic experts arrived in Pyongyang on Wednesday to promote cooperation in trade, economics and science.

Trump overtures ignored

Trump's repeated offers to meet Kim — most recently on Monday, when he told reporters aboard Air Force One en route to Tokyo that he "would love to" talk with the North Korean leader during his Asia tour — have been met with silence.

"Personally, I do not believe the North Korean side ever had any intention of agreeing to a meeting between the two leaders," said Yakov Zinberg, a professor of international relations at Tokyo's Kokushikan University, who is originally from St Petersburg.

Zinberg said to DW that Trump's advisers wanted the meeting to go ahead in a bid to drive a wedge between North Korea and Russia, "but that was always going to be a difficult thing to achieve."

"Moscow knew exactly what was going on and used its own tactics to halt it, by arranging parallel meetings between the North Korean foreign minister and the Russian president in Moscow," he said, adding that Pyongyang was happy to cooperate.

Unlike in previous years, North Korea is showing to the US, South Korea and Japan that it is more confident in its international standing "because they have a superpower behind them," Zinberg said.

He highlighted the advanced weapons and technology — as well as fuel and food for North Korea's civilian population — that not long ago were out of reach because of international sanctions, but which are now available to Pyongyang thanks to Moscow's backing.

"The message is that North Korea is no longer alone, that they are a power and that they no longer need to respond every time Trump speaks," Zinberg said.

This creates a challenge for the US president, Choo said. What price must he pay to get Kim back to the negotiating table, and is that price too high for Washington's allies in the region?

"I think he is already thinking about the next step, the moves he can make to reach a compromise in the war in Ukraine and then make some sort of agreement on the [Korean] Peninsula so he can get a Nobel Peace Prize," said Choo.

Will Trump recognize North Korea's nuclear status?

The fear is that the carrot he is willing to dangle in front of Kim would be recognizing North Korea as a nuclear state. It is something Trump hinted at before heading for Asia, when he told reporters, "I think they are sort of a nuclear power. I mean, I know how many weapons they have. I know everything about them."

Accepting Pyongyang as a nuclear power would effectively and abruptly put an end to the long-established position of the US and its allies that North Korea needs to abolish its nuclear arsenal for international sanctions to be lifted and for the nation to rejoin the global community.

But recognizing North Korea as a nuclear power would expose non-nuclear South Korea and nearby Japan to even greater security risks and, in all likelihood, trigger an arms race across the region.

"For North Korea, that would be an enormous prize and one that could draw Kim back into discussions," said Choo. "But from South Korea's perspective at this point in time, before other agreements and guarantees are in place, that cannot be an acceptable concession."

Edited by: Karl Sexton