THE last time that America almost risked a pre-emptive strike on North Korea the gamble offered a spectacular pay-off. Ashton Carter, a leading architect of that plan, recalls that his scheme for bombing the Yongbyon nuclear facility in 1994 assumed that in one or two days the entirety of the regime’s nuclear programme could be levelled and entombed in rubble. Mr Carter, who went on to become defence secretary in the Obama administration, now thinks that an American first strike would only put “a significant dent” in North Korea’s arsenal of nuclear devices and bombmaking sites. “The difference today is that the North Koreans are very good at hiding, burying and moving around their nuclear infrastructure,” says Mr Carter, now at Harvard University.

If the potential upsides of a strike have shrunk, the risks have grown hugely. The crisis of 1994 saw Kim Il Sung thwart international inspections and threaten to put plutonium from Yongbyon into half a dozen primitive bombs. Since then power passed to the despot’s son and in 2011 to his grandson, Kim Jong Un, a young man in a hurry who has to date never met a foreign leader, even from China, the closest his all-but-friendless kingdom has to an ally. North Korea has tested six nuclear devices between 2006 and 2017, including what appeared to be a hydrogen bomb, and produced enough plutonium and uranium for possibly dozens more warheads. Its missiles credibly threaten American territory in Guam, Hawaii or even the continental United States, even if officials do not believe a North Korean nuclear-tipped rocket can yet reach an American city.

Just because war in Korea would be unspeakably dangerous does not mean that it will not happen. Sober officials with long careers in Asia policy talk of being more fearful than at any time in recent memory. America is governed by Donald Trump, who revels in matching North Korea in bluster. He has called Mr Kim “Little Rocket Man” and a “sick puppy”, and promised that continued North Korean threats to America “will be met with fire and fury like the world has never seen”. Mr Trump has at times called diplomacy with the Kim regime “a waste of time”. He is also scornful of allies and alliances, causing one Japanese expert to identify a grave concern: “that Trump will come up with a military option and not take the costs seriously.” It is not just Mr Trump. The generals seen as a steadying influence on the president have given warnings that the Kim regime cannot be permitted to build weapons that threaten American territory.

General Joseph Dunford, chairman of the joint chiefs of staff and a man who wields his influence discreetly, last year chided anyone who thinks it unimaginable that America might use force to check a North Korean nuclear menace. “What’s unimaginable to me is allowing a capability that would allow a nuclear weapon to land in Denver, Colorado,” he said. In August 2017 H.R. McMaster, a lieutenant-general who is national security adviser to Mr Trump, scolded an Obama-era predecessor, Susan Rice, for suggesting that their country could contain and deter a nuclear-armed North Korea, as it did the Soviet Union. “She’s not right,” chided Mr McMaster, asking how “classical deterrence theory” could apply to so brutal a regime.

On manoeuvres

Even the defence secretary, James Mattis, a cerebral former Marine general who says his job is to “buy time for our diplomats” to solve the North Korean crisis, has weighed in. Put on the spot by reporters in September 2017, he insisted that there are military options that would not imperil Seoul, the South Korean capital, though its 10m inhabitants live within range of the North’s artillery and missiles. Such options exist, he said, “but I will not go into details.”

Others sound less certain. Mr Carter notes—with tact—that retaliating against a foreign attack is the standing policy of the North Korean armed forces. “If the US and South Korea decided to initiate a strike, we would have to make sure that we were thoroughly prepared for a full-on conflict,” he says. Invited to contemplate military options that would not put Seoul in harm’s way Abraham Denmark of the Wilson Centre, and a Pentagon official during the Obama era who worked on Korea policy, answers simply: “I can’t imagine what those could be.”

Discussions of Korea strategy quickly drift into seemingly impossible tangles, involving deadly Stalinist court politics and fantastical perils. Official reports detail the North’s nuclear, biological and chemical arsenals, and artillery pieces in hardened bunkers just north of the demilitarised zone (DMZ) that divides the two Koreas, which some analysts estimate can fire 10,000 rounds a minute at Seoul. A Pentagon report of 2015 talks of North Korean drones, midget-submarines and of commandos who may attack targets in South Korea “via suspected underground, cross-DMZ tunnels”. Mr Mattis has said a Korean conflict “would probably be the worst kind of fighting in most people’s lifetimes”.

Still, responding to presidential demands for more and better options, officials are debating possible “preventive” strikes, a term denoting actions taken earlier than “pre-emptive” attacks in response to an imminent threat, like a missile being readied for launch.

Untangled logic

At root, however, debates about Korea strategy turn on two starkly straightforward questions, spelled out in interviews with serving and former defence and national-security officials, diplomats and spies, including several with personal experience of negotiating with North Korea. First, will China ever break decisively with North Korea, its infuriating neighbour but valued buffer against the world? Second, can Mr Kim be deterred? For if he cannot, then any responsible American president must contemplate a strike, risking what the Japanese expert summarises as “tens of thousands of casualties today to prevent millions tomorrow”.

Aides to Mr Trump boast that the president’s resolve explains China’s support for UN Security Council sanctions of unprecedented severity, including curbs on North Korean exports of coal and textiles and on flows of oil and refined petroleum from China. A senior State Department official recalls Mr Trump’s order to strike Syria with Tomahawk cruise missiles in April 2017, during dinner with the Chinese president, Xi Jinping, at Mar-a-Lago, his Florida estate. That strike, enforcing a red line over Syria’s use of chemical weapons, “put military action back into our diplomacy”, says the official. “It was an important data point that China internalised.”

In fact China has yet to abandon a long-standing hierarchy of Korean horror in which a nuclear-armed North ranks second. For China, it is pipped by the prospect of a chaotic fall of the Kim regime, followed by a reunification of the two Koreas on Western terms, lining China’s border with American allies and high-powered American radars (or worse, hulking GIs in Oakley sunglasses).

Team Trump has tried sweet reason. Rex Tillerson, the secretary of state, joined Mr Mattis in assuring China publicly that as it pursues the denuclearisation of the Korean peninsula, America has no interest in regime change or accelerated reunification, seeks no excuse to garrison troops north of the DMZ and has no desire to harm the “long-suffering North Korean people”, as distinct from their rulers.

Revealing a once closely held secret, Mr Tillerson told the Atlantic Council, a Washington think-tank, last December about “conversations” with China about how the two countries might secure loose nuclear weapons should North Korea fall into chaos. This included assurances that American forces would retreat south of the DMZ when conditions allowed. Less sweetly, the senior official at the State Department says that when Mr Tillerson first met his Chinese counterparts, Yang Jiechi and Wang Yi, in March 2017, he told them that “we are out of time” and to drop their long-standing view of North Korea as an asset that keeps America usefully tied up.

Mr Tillerson told China that it can help America do more “the easy way or the hard way”, with the hard way meaning secondary sanctions on Chinese entities that trade with North Korea, and credible threats that Mr Trump is “serious about the military option if we cannot resolve this diplomatically”. Addressing that hierarchy of horror, the aim is to convince Chinese leaders that the very thing they fear most—instability next door, followed by an Asian nuclear-arms race—will be brought about by continued toleration of America’s worst fear, namely North Korean nukes.

Put that way, the Korean dilemma arguably revolves around a single question: is Mr Trump bluffing? Should North Korea, China and the wider world believe that America will use force to prevent Mr Kim from building a nuclear missile that can strike Washington, DC, or Los Angeles?

Team Trump is at pains to explain why the boss is not bluffing, and why 2018 is, in the words of one senior administration official, “a very dangerous year”. That official pointedly praises Israel for twice launching air strikes against suspected nuclear weapons sites, once in 1981 against the Osirak reactor being built by Iraq, and in 2007 against a reactor in Syria allegedly under construction with North Korean help.

Strike one, strike two…

The official calls those strikes “textbook cases” of preventive action. He draws attention to a Trump tweet in late December, linking to a television interview that Mr Trump gave as a private businessman in 1999, urging America to “negotiate like crazy” with North Korea but, if talks failed, to “do something now” before warheads are aimed at New York and other cities.

Strikingly, though, when asked point blank whether Mr Trump has already set red lines that North Korea may not cross, officials will only reply that as a general rule, they are very careful about drawing red lines. Though news outlets have reported debates about giving North Korea a “bloody nose”, an official calls that phrase “a fiction of the press”.

Insiders deny that the Trump administration is dividing into camps of hawks and doves, with each taking a different view of the utility of talks. A clearer divide turns on relative optimism or pessimism about Mr Kim’s intentions, with Mr McMaster a leading voice of doom (he has compared this moment of geopolitical peril to 1914). In particular, pessimists doubt North Korea’s claim that it wants nuclear weapons that can hit America for self-defence.

Undeterred?

Logic, and Mr Kim’s own words, point to a nuclear programme with grander ambitions, perhaps to “drive the US from the peninsula” or reunify Korea under the North’s flag, argues the senior administration official. “Why should a regime starve a couple of million of its own people to death, expose itself to punishing sanctions, [and] allow itself to be isolated by all its friends, merely to gain a deterrent that they already had for 60 years, from artillery pieces pointed at Seoul?”

Several officials and ex-officials who see the value of frightening Mr Kim to the negotiating table hope privately that Mr Trump is bluffing, believing that a limited strike would risk massive retaliation. Even narrowly-focused operations North of the border are deemed risky. In late 2016 Mr Obama’s National Security Council organised a war game, asking military, diplomatic and intelligence officials to simulate a mission to secure nuclear weapons in a North Korea tumbling into instability.

Participants call the exercise deeply sobering, with so many American troops needed to secure the large number of nuclear sites that it could take months to build them up, losing any element of surprise, and raising seemingly insuperable questions about when to evacuate Americans from the region without triggering chaos. An unclassified letter sent by the Pentagon to Congress in November 2017 offered the assessment that only a ground invasion could find and secure all weapons sites.

A senior American official recalls being asked by foreign counterparts why Mr Kim could not simply be killed. In reply he would point to the outside world’s dangerous lack of knowledge about what orders the leader’s death might trigger: “We seriously don’t know that there isn’t some sort of automatic doomsday process that pulls down the pillars of the temple.” The same official asked military colleagues for “horse’s head on the pillow” options that would terrify Mr Kim without triggering a full-scale response. “Nobody I spoke to in the military had an idea that could reliably thread the needle,” he says.

Scenarios for limited strikes could include the shooting down of a North Korean ballistic missile test. But a failure would damage the credibility of American defences. There is also a dangerous paradox attached to any action launched on the grounds that North Korea is deemed deaf to reason, notes Joseph DeTrani, a former intelligence officer and commentator for “The Cipher Brief”, a national-security website, who is also a semi-official envoy entrusted with meeting senior North Korean diplomats.

If trust vanishes, North Koreans “may see an imminent threat coming to them that is not an imminent threat”, disbelieving assurances that a strike is limited. In his experience, the country’s diplomats are professional and informed about the world. But that only helps if their advice reaches core leaders, who also hear from “hardliners in North Korea [whom] we do not know,” cautions Mr DeTrani. He disagrees with colleagues (and there are many) who call Mr Trump’s tweets unhelpful. On balance it is positive for North Koreans to hear directly from the president, he says. They understand bombast.

Optimists note that America has real points of leverage, even without force. Mr Carter urges step-by-step “coercive diplomacy”, setting out specific sticks and carrots for discrete North Korean actions, from missile tests to underground nuclear tests. If China proves incapable of playing a positive role, he recommends it is “sidelined”.

Several officials say that China’s willingness to toughen sanctions is mostly about managing America, which is seen as one of two irresponsible powers, alongside North Korea, distracting Chinese leaders from their domestic priorities. “The Chinese are more upset with the North Koreans for waking the American giant,” says an American official.

China is now enforcing UN trade embargoes on North Korea more strictly, in part to ward off American sanctions targeting specific Chinese banks and oil traders, though diplomats still deplore Chinese “salami-slicing” of each new sanctions plan. By a process of elimination, China now backs “pressure that will placate the Americans without being strong enough to [make the Kim regime] collapse,” says the official. Meanwhile, China continues to argue for America to freeze military exercises and curb deployments of advanced weapons in Asia. China is always “willing to bargain away the American military footprint”, growls a second official.

A final camp combines scepticism about North Korea’s motives—dismissing Mr Kim’s claims to need nuclear weapons as a deterrent—with (relative) optimism about sanctions. A Western diplomat says that North Korea believes that, if it can become the only nation with a long-range nuclear capability other than America, Britain, China, France and Russia, it will be welcomed to an “elite club”, free of all sanctions, “which is pie in the sky”.

This camp would use North Korea’s ambitions against it. Daniel Russel, former assistant secretary of state for East Asian and Pacific affairs during the Obama era, shares the pessimists’ belief that North Korea does not need nuclear weapons for deterrence, securing its safety with its ability to bombard Seoul. Nor does it need missiles—it can already detonate a nuclear device smuggled into South Korea, even if that would be suicidal.

Mr Russel argues that the North’s goal is money and other concessions. If through sustained sanctions “North Korea is denied the pay-off, the ransom it is seeking, it hasn’t actually achieved the [right] return on investment on the nuclear programme,” says Mr Russel, now at the Asia Society. A sense of being squeezed without reward is spreading discontent among the elites, he says. “The ability to limit Kim’s ability to govern, via sanctions, is the best leverage we have.”

Ironically, given all the focus in Washington on Mr Trump’s impulsive ways, insiders worry most about a crisis that is thrust upon him. They fear that China and North Korea are both waiting Mr Trump out, hoping that he loses the White House or become distracted by other crises.

Mutual incomprehension

Mr Denmark speaks for several officials when expressing dread about Mr Kim misjudging some fresh provocation. In 2010 the North sank the Cheonan, a South Korean patrol ship, killing 46 sailors. He fears Mr Kim trying a similar act today, thinking that America will not respond. The North might overreact to American demonstrations of will, such as bomber flights off the coast, says Mr Denmark. “What’s to stop the North Koreans thinking that’s the beginning of an attack? That keeps me up. Who has launch authority on the North Korean side in the middle of the night?”

On the other side stands Mr Trump, a wild card who may soon face risks he deems intolerable while lacking any good options. “The president may be forced to take action,” a US official says. “The potential for conflict is very high.”