A lot can change in a few months. The year began with President Donald Trump threatening to use his nuclear button against North Korea. This weekend though there was talk - albeit by Fox News - of him deserving the Nobel Peace Prize for bringing about the historic North-South Korean summit of the past few days.

But before anyone gets carried away and a collective euphoria sets in, it’s worth bearing in mind that as with all historic deals, the devil is in the detail. That’s not to say that recent events have not been truly remarkable and given great cause for optimism.

As the New Yorker magazine reflected in its coverage this weekend, images do matter. Back in 1938 the world saw Neville Chamberlain shaking hands with Adolf Hitler. Then in 1985 it saw Ronald Reagan sitting by the fireside with Mikhail Gorbachev.

Likewise today, the pictures of Kim Jong Un, the North Korean leader stepping over the ankle-high wall that officially divides the two countries and holding hands with Moon Jae-in, the President of South Korea, will go down in history.

The words used by both leaders too were unprecedented in talks between the two countries.

“As I walked over here, I thought, ‘Why was it so difficult to get here? The separating line wasn’t even that high to cross,’ ” said Kim, as the world’s media soaked up the moment.

In a meeting marked by smiles, handshakes and embraces in the heavily fortified Demilitarised Zone that has divided the Koreas for more than six decades, Kim and Moon announced in their “Panmunjom Declaration” (Panmunjom was the site of their meeting) that they would work with the United States and China this year to declare an official end to the 1950s Korean War, and establish a permanent peace agreement.

“The two leaders declare before our people of 80 million and the entire world there will be no more war on the Korean peninsula and a new age of peace has begun,” the two sides said.

A “new milestone” in the history of the two countries has been reached they stressed and “complete denuclearisation” was their shared objective.

The goodwill even seemed to rub off on Trump himself. On Friday morning he appeared to have been watching the footage from Panmunjom.

Lately of course Trump’s language about Kim has changed dramatically. Where once he threatened to “totally destroy” the country over "little rocket man's" provocations, he is now calling Kim “very open” and “very honourable.”

His initial tweet about the summit though was relatively cautious: “After a furious year of missile launches and Nuclear testing, a historic meeting between North and South Korea is now taking place. Good things are happening, but only time will tell!”

Just ten minutes later, however, Trump changed his tone and appeared to claim the credit : “KOREAN WAR TO END! The United States, and all of its GREAT people, should be very proud of what is now taking place in Korea!”

Not to be outdone meanwhile, back across the ankle-high wall that officially divides the two Koreas, the North’s official KCNA news agency credited Kim with the success of the summit.

“The historic meeting at Panmunjom came to be realised thanks to the supreme leader’s ardent love for the people and will for self-determination independent of outside influence", it said.

In characteristically colourful language that was the perfect counterweight to Trump’s bragging, the news agency went on to say the meeting was “accompanied by sunny April weather” and “born with a new energy of endless joy and hope”. A band played “jolly music to heighten the welcoming atmosphere”, it said.

So far, so good, but in a day that produced dramatic images and an agreement on a common goal of a “nuclear-free” peninsula, both Korean leaders stopped short of spelling out exactly what that meant or how it might come about.

The meeting too was short on specific commitments and failed to clear up the question of whether Pyongyang is really willing to give up nuclear missiles that now threaten the United States.

While none of the agreed-upon Panmunjom Declaration points are major concessions or shifts, each does at least reflect long-expected confidence building measures. This inter-Korean meeting too is in many ways primarily a prelude to the upcoming summit between Kim and Trump.

According to the US based geopolitical intelligence publication Stratfor, when seen from a South Korean perspective Moon’s meeting with the North offers a brief moment to lead in facilitating US -North Korean relations.

“The opportunity for a lasting US-North Korea deal will fall apart if either Washington or Pyongyang backs out, so South Korea is trying to use this summit to keep the momentum going and get a commitment from the north on further visits and other regular dialogue channels, both of which it secured,” observed Stratfor analysts.

But many within Washington remain sceptical of Pyongyang’s sincerity and have been consistently wary of the North Korean leader’s motives for some time.

Only last December H.R. McMaster, who was then Trump’s national-security adviser, said in an interview with Fox News that North Korea wants to use its nuclear-weapons capability for "blackmail, and then to, quote, ‘reunify’ the peninsula under the red banner”.

A little later in January, Mike Pompeo, who was then head of the CIA and is now US Secretary of State, said something similar. And, in February, Admiral Harry Harris, the head of the US Pacific Command, told the House Armed Services Committee, “I do think he”- Kim -“is after reunification under a single Communist system”.

While on the face of it Kim’s promise to end “the history of confrontation” appears genuine, it continues to ring alarm bells for many analysts and veterans of negotiations with North Korea who worry that Kim is now getting ready to play the United States.

These sceptics and doubters argue that while the Trump administration’s tough sanctions no doubt had some role in pushing the North toward the current summit, they are cautious that perhaps this is precisely the scenario Pyongyang itself sought from the beginning.

Clearly, there are a number of potential hazards for the United States in Friday’s deal. The most obvious of these will be reaching agreement on the precise definition of “denuclearisation” and how it will be achieved and verified. Barely a year ago, it appeared as if nothing would get North Korea to budge on its nuclear weapons programme and its insistence of being recognised as a nuclear state.

Now say doubters, it is making public “concessions” before it sits down with US officials making for confusion over what, precisely, Pyongyang wants or what it is willing to do.

“North Korea cannot be trusted to denuclearise unless we know exactly what that means and under what conditions,” says Emil Dall, a research fellow at the Royal United Services Institute (RUSI) for Defence and Security Studies in London. “This deal doesn’t give us any detail about that.”

Trust remains in short supply in Washington too when it comes to the North Korean leadership.

“When looking at our own interests, we need to decide what North Korean weapons plan we are willing to accept. Despite much happy-feeling talk from Pyongyang, it seems highly unlikely Kim will give up all his nuclear weapons,” says Admiral James Stavridis, formerly the 16th Supreme Allied Commander at Nato and now Dean of the Fletcher School of Law and Diplomacy at Tufts University.

“While I believe we should accept a limited arsenal, with an inspection regime and a diminution of the ballistic missiles to deliver them, if we are not going to do so we should be prepared to walk away from the table,” Stavridis stated.

In the interim while working through this problem Washington needs to listen more to the South Koreans some observers insist. Moon and his government in Seoul, they argue, understand Kim in “three dimensions” and have a clear-eyed view about the dystopian nation over which he rules.

This is a very different take from those within the Trump administration who see the North and its leader one dimensionally and no more than a “semi-crazy dude with a really bad haircut”, says Stavridis.

The precise definition of “denuclearisation” is however only one of numerous challenges US officials will face when they sit down with their North Korean counterparts.

Whatever the outcome of Trump’s summit there is always the risk of being seen to help normalise a regime with an appalling human rights record. Then there is the diplomatic tripwire of potentially driving a wedge between the US and South Korea, something that would in turn generate friction with China and Japan.

Takashi Kawakami, professor of international politics at Tokyo’s Takushoku University, said any dilution of the US-South Korea alliance would ratchet up regional tensions.

“Japan would become the front line,” he said. “Japan's security risks would increase. The Chinese navy would probably come into the Sea of Japan, as would the Chinese air force.”

At home, meanwhile, Trump too will likely find himself under extreme pressure from the political uber-hawks within his administration of which currently there is no shortage. For them Kim is not to be trusted on any level and has already done enough in their eyes to warrant some kind of military response.

At the very least they will be unwilling to endorse any weakening of sanctions on Pyongyang, even though Friday’s promises of cross-border trade and economic cooperation would most certainly require sanctions relief.

In other words, the diplomatic road during the forthcoming summit between Trump and Kim remains a tricky one to say the least. In any normal circumstances you might expect the two sides to have worked out the outlines of the agreement before the two heads of state sat down together, but that’s unlikely to be the case this time, which means just about anything could happen.

“An obvious complication is that we are dealing here with two leaders who can’t be trusted at all," says Stephen M Walt, Professor of International Relations at Harvard University.

“There’s no reason to take anything Kim or his associates might say at face value, and unfortunately the current US president is also a proven and chronic liar, so neither has any reason to believe a word the other says.”

That said, its pretty much a given that Trump will want to milk the summit for all its diplomatic worth regardless of the concerns among advisers in his administration.

The New Yorker's John Cassidy hit the nail on the head when he said that Trump is a man who values visuals above virtually all else.

“He is seemingly intent on providing the world with an image even more memorable than the ones from Panmunjom: a picture of himself and the leader he once dubbed “Little Rocket Man” shaking hands,” noted Cassidy.

Yesterday as many people were still rubbing their eyes in disbelief at the images from Panmunjom on Friday, the Saturday edition of North Korea's Rodong Sinmun newspaper, ran four pages dedicated to the summit.

Even in Kim’s secretive state the diplomatic cat it seems is finally out of the bag and expectations are high. But the devil still lies in the detail of that summit when Trump and Kim come face to face.