The focus of weeks of hostile rhetoric on the Korean peninsula has shifted from nuclear war to dialogue, but analysts warn the road to formal talks is longer and more challenging than it has ever been.

So challenging, in fact, that some experts believe dialogue is not even a realistic option given that North Korea is as committed to its demand for recognition as a nuclear power as the United States is to refusing it.

With three nuclear tests under its belt, these experts argue, North Korea is no longer the country that negotiated a 1994 nuclear deal with the US or reached a 2005 denuclearisation accord under the six-party talks framework.

During a trip to Seoul, Beijing and Tokyo last week, US Secretary of State John Kerry repeatedly stressed Washington was ready to talk to Pyongyang provided it was serious about reining in its nuclear programme.

The response from North Korea was to issue a list of essentially impossible pre-conditions, including the withdrawal of United Nations sanctions.

For cup-half-full observers, the fact that Pyongyang chose to engage on the subject of talks at all -- no matter how unrealistic its demands -- was a welcome move.

And Kerry chose to take the North's response as an "opening gambit" which, while "obviously" unacceptable, at least opened the door to further discussion.

But where would that discussion lead?

If the North's initial position is wilfully unrealistic, so, according to some analysts, is the US stance -- predicated on the assumption that a way exists to persuade Pyongyang to abandon its nuclear weapons.

That the North has devoted so much effort and money into developing its nuclear arsenal is proof, says Victor Cha of the Center for Strategic and International Studies, that it is interested in more than just piling up bargaining chips.

"It actually wants to acquire these capabilities and be accepted by the world as a nuclear state," Cha said. "It is is unlikely to trade them away."

Daniel Pinkston, a North Korea expert with the International Crisis Group, believes the current diplomatic thinking on North Korea labours under the illusion that Pyongyang has a fallback, compromise position.

In reality, Pinkston argues, the North's "military-first" policy, maintained by its new young leader Kim Jong-Un, means the regime's legitimacy rests on a perception of strength, making it impossible for it to back down.

"It just isn't going to go anywhere," Pinkston told AFP.

"It's a bit like being infatuated with someone who can't stand you. You're desperately searching and prodding to find something you share in common, but there's nothing there."

Those who see dialogue with the North as inherently fruitless suggest the only real option is robust deterrence and containment -- a strategy backed by Siegfried Hecker, a leading expert on the North's nuclear programme.

"It has been clear for some time that North Korea will not give up its nuclear weapons," Hecker wrote in Bulletin of the Atomic Scientists.

"So what we should have focused on is to make sure things don't get worse," Hecker said.

Proponents of dialogue argue that while diplomacy might not secure solutions, it can help to point them out.

Joel Wit, a former US negotiator with North Korea, believes contact with North Korea is crucial to clarify its intentions in a way that cannot be done by parsing the words of Pyongyang's bellicose state media.

"We might learn that there are peaceful paths forward or that the North is indeed bent on confrontation," Wit and Johns Hopkins University researcher Jenny Town wrote in an article for Foreign Policy magazine.

"Either way, clarity is essential given the seriousness of this situation."

The Korean peninsula has been caught in a cycle of escalating military tension since the North carried out its third nuclear test in February.

Pyongyang may have dialled down the pitch of its hostile rhetoric in recent days, but the tensions and accompanying risk of a misstep that could spiral out of control remain.

And the North has shown no sign of reversing its surprise move earlier this month of closing down the South-funded Kaesong joint industrial complex -- a key source of hard currency for the regime in Pyongyang.

Given the sensitive atmosphere and the apparent unbending incompatibility of the North Korean and US positions, one way forward would be for Washington to remove itself from the equation -- or at least distance itself.

Paul Carroll, programme director at the Ploughshares Fund, a US-based security policy think-tank, believes the US is looking to have South Korea take responsibility for opening and moulding a dialogue.

"I suspect that is what the conversation in early May will be about," Carroll said, referring to planned White House talks between Barack Obama and South Korean President Park Geun-Hye.

"It's a strategy Washington can sell domestically, that Seoul is on the frontline, understands this better than anyone, and should take the lead," Carroll said.

"It still won't be easy to realise a dialogue, but there's a better chance," he added.