In the 16 months Donald Trump has been in office as president of the United States, he has celebrated "progress" on the issue of North Korea and its nuclear weapons as one of his major successes.
His supporters have even called for him to be awarded the Nobel Peace Prize for his efforts to engage the North Korean regime and its leader, Kim Jong-un.
At first, it seemed to be working. After starting his presidency exchanging insults with the secretive leader – with Trump dubbing Kim "little rocket man" and Kim branding Trump a "dotard" – denuclearisation talks seemed to be progressing, as Kim met with US Secretary of State, Mike Pompeo, and held an historic summit with South Korea's president Moon Jae-in.
The talks were followed by a shock announcement that North Korea had suspended nuclear and long-range missile tests ahead of a new round of negotiations with South Korea and the United States.
But now, Trump and the South Korean President have been holding urgent discussions to ensure the North Korea-US summit remains on track.
It is now looking unlikely to go ahead after North Korea said it would not hold talks with South Korea unless their demands that the South stops conducting military drills are met.
While the US President seems surprised by the U-turn, experts such as Brian Klaas of the London School of Economics are suggesting this was North Korea's plan all along.
"Trump's early victory lap on Twitter and the media hyperventilation over a possible Nobel Prize is like a cyclist who celebrates prematurely only to crash before the finish line," he told HuffPost UK.
"It was never credible to believe that insulting Kim Jong-un on Twitter was the solution to decades of a slow-burning and deeply complicated diplomatic impasse."
How Did We Get Here?
The relationship between the two countries got off to a bad start under Trump, who last year derided Kim Jong-Un as a "maniac," referred to him as "little rocket man" and threatened in a speech last year to "totally destroy" North Korea, a country of 26 million people, if it attacked the United States or one of its allies. Kim responded by calling Trump a "mentally deranged US dotard".
What Changed?
Last month, everything changed: North Korea announced it had suspended nuclear and long-range missile tests ahead of a new round of negotiations with South Korea and the United States.
Trump appeared to downplay the fact the announcement came after Kim had declared his nation's nuclear force as complete, after a slew of weapons tests that included the underground detonation of a purported thermonuclear warhead.
North Korea had also carried out flight tests of three intercontinental ballistic missiles.
What's Supposed To Be Happening?
Moon and Trump are set to meet on Tuesday in Washington before North Korean leader Kim Jong Un meets with Trump on 12 June in Singapore.
What Changed (Again)?
North Korea's chief negotiator Ri Son Gwon said on Thursday it would not hold talks with South Korea unless their demands were met, taking issue with the US-South Korean air combat drills known as Max Thunder.
It came a day after it threatened to pull out of the summit with the United States.
Further dampening the mood, a spokesman for North Korea's Red Cross Society demanded on Saturday that South Korea's government should send North Korean female restaurant workers back to their home "without delay" to show the will to improve the inter-Korean ties, the North's Korea Central News agency said.
And Trump's decision to back out of the Iran nuclear deal may also have an impact.
Mark Seddon, former speechwriter to UN Secretary Ban Ki-moon and Adjunct Professor in International Relations at the University of Columbia, NY, told HuffPost UK: "Their aim to ensure copper bottomed guarantees for the security of their deeply repressive regime.
″ I suspect that China has been a key driver in encouraging Kim Jong-un to make what have been some quite extraordinary moves that were reciprocated by Donald Trump."
"The North Koreans could certainly see an opportunity - one that they have never seen with a US President before - but they will also have seen how Trump can simply walk away from a nuclear treaty with Iran."
Why Would North Korea Play Trump?
North Korea is economically and politically weak and has been a pariah on the international stage for decades.
The country's nuclear programme, developed at the expense of providing basic living conditions for the majority of its citizens, has been its only leverage.
The increase in rhetoric between Kim and Trump last year effectively provided the cover to advance it to the point it directly threatened the Untied States which, in turn, has now led to a diplomatic coup for North Korea - a possible meeting with the President on equal terms.
Klaas said: "Kim Jong-un has continued his family's longstanding goal of acquiring nuclear weapons as a trump card to stop military action against their dynastic regime," he told HuffPost UK.
"He is likely not going to give them up without extracting concessions that no American President should accept. Trump would be best served by listening to experts who will help him avoid getting played badly—and avoid unforced errors from a President who believes he knows things that he does not."
What Happens Next?
That all depends on the next few days and the US and South Korea have so far been vague about next steps.
Moon and Trump spoke over the phone for about 20 minutes this weekend, and exchanged their views on North Korea's recent reactions, South Korea's presidential office said without elaborating.
"The two leaders will work closely and unwaveringly for the successful hosting of the North Korea-US summit set on June 12, including the upcoming South Korea-US summit," the presidential official said.