Be afraid, be very afraid: Trump's bluster risks turning nuclear war into the acceptable face of combat
When nuclear weapons were deployed against a US enemy at the end of World War II, for the first and last time to date, the American public initially mostly supported their use. That changed when the fallout - killing tens of thousands within seconds around the Japanese cities of Hiroshima and Nagasaki - became apparent.
It's a sentiment which has lasted for decades, and, if anything, only appeared to get stronger - until recently.
When President Barack Obama paid tribute to the people of Hiroshima in May 2016, he urged the international community to "choose a future when Hiroshima and Nagasaki are not considered the dawn of atomic warfare but as the start of our own moral awakening".
At the time, nobody would have predicted the victory of Donald Trump in the elections the following year, however.
During his first year in office, Trump has shattered the cautious and history-burdened way we used to discuss nuclear weapons.
On Tuesday evening, the president further escalated his war of words with North Korean leader Kim Jong-un, asserting his "nuclear button" was "much bigger & more powerful" than his adversary's. He went on to threaten that the US arsenal "works".
Kim had previously taunted Trump in a New Year's Day speech, saying that his nuclear button was always on his desk.
The president's response a day later was only the latest escalation of rhetoric - last summer, Trump had already warned North Korea of "fire and fury" - and his remarks have made analysts wonder whether Trump is aware of the catastrophic impact an activation of either of those buttons would have.
Observers from the United States and abroad criticised the remarks as "infantile" and ill-advised.
"Trump plays with the subject so carelessly and recklessly as if it were some kind of video game," argued Aaron David Miller, a fellow at the Woodrow Wilson International Centre who has advised several secretaries of state. "My head's exploding," he wrote on Twitter.
Whereas Trump may be the first US president to engage in such rhetoric, there appears to be some precedent for it. The way Trump discusses nuclear weapons may fall into a pattern that has been observed among military officials in the past, as researchers pointed out on Tuesday.
They were referring to a 1985 study by Carol Cohn who analysed remarks that compared nuclear war with "an act of boyish mischief." Cohn argued they were an expression of a "competition for manhood," and "a way of minimising the seriousness of militarist endeavours, of denying their deadly consequences," concluding they posed a "tremendous danger" in real life.
That's especially true if you're the president of the United States.
The worry is that Trump's remarks are eliminating the reasoning that may have prevented world leaders from resorting to nuclear weapons ever again since World War II.
The best-known explanation for this reluctance relies on the concept of deterrence, which assumes that the repercussions of a nuclear war would be so catastrophic - some scenarios predict a "nuclear winter" which would wipe out the majority of humanity - that no leader would want to start such a conflict. For that reason, several nations have committed to not using nuclear weapons first.
To some, Trump's August "fire and fury" remarks indicated the US commander in chief may be willing to launch an attack against Pyongyang without being attacked first - appearing to mark a reversal of decades-long implicit consensus, even though Trump later softened his stance at the insistence of his advisers.
A second theory for why nuclear weapons have remained ostracised for decades frames the decision to trigger their use as a 'moral taboo'. In her book 'The Nuclear Taboo', researcher Nina Tannenwald writes that US leaders have been dissuaded from their use by moral restraint. Relying on historic analysis, Tannenwald argued that "powerful revulsion associated with nuclear weapons had played a role in inhibiting their use".
Compare that with Trump's references to Kim as 'rocket man', or his proclamation last August that his "first order as president was to renovate and modernise our nuclear arsenal".
"It is now far stronger and more powerful than ever before," Trump wrote.
The former chairman of the Joint Chiefs of Staff under Obama, Admiral Mike Mullen, warned on Sunday that the United States was now "closer to a nuclear war with North Korea" than ever before. Trump is not the only one to be blamed for that, as North Korea's continuing missile tests have put significantly more pressure on the president.
But analysts fear his response to that pressure may normalise the possible future use of nuclear weapons to a dangerous extent.
A Gallup poll last September found US public support for attacking North Korea was already extraordinarily high, considering the likely fallout.
An extensive Stanford study last year similarly found that a majority of citizens would be in favour of relying on nuclear weapons to attack civilians in a non-nuclear adversary.
Sixty per cent of Americans would accept the deaths of two million Iranian civilians in such an attack, for instance, if the strike spared the lives of 20,000 US military personnel.
"These findings highlight the limited extent to which the US public has accepted the principles of just war doctrine and suggest that public opinion is unlikely to be a serious constraint on any president contemplating the use of nuclear weapons in the crucible of war," wrote the two researchers, Scott Sagan and Benjamin Valentino.
The social media outrage over Trump's Tuesday remarks may have been fierce, but public acceptance of his threats already appears far more widespread than nuclear disarmament advocates would hope.