This week is the 68th anniversary of the US and British firebombing of the German city of Dresden, in the closing months of the Second World War. In a series of raids over three days, high explosive and incendiary bombs were dropped on the city to create a firestorm of such ferocity that it melted human bodies. Up to 25,000 people died in the attack, which left the city centre in ruins.
To this day, the bombing of Dresden - defended at the time as an assault on German communications and factories - is widely considered an act of terror against civilians and refugees huddled in the city. This is not the place to discuss the morality of the action, but it serves as a marker to judge how far we have moved since the 1940s in resolving international disputes.
Over the past few days, Washington and its allies have been promising "significant action" against North Korea for its third nuclear test. Pyongyang did this in defiance of warnings of dire consequences from the international community, including its ally and supporter, China. Susan Rice, the US ambassador to the United Nations, says the organisation will make a "swift, credible and strong" response.
But what would that response be? Not military action. There will be no bombing of Pyongyang, because Seoul, the South Korean capital, is a mere 50 kilometres from the border and within missile range of the North Korean army. As the US is bound to defend South Korea, any military action revives memories of the Korean War of the 1950s, at a time when the Chinese military is becoming far better equipped.
There is no question that the need to stop North Korea becoming a nuclear power is a priority for the US. The Kim dynasty, represented by the 30-year-old Kim Jong-un, is the most flagrant violator of the already fraying nuclear Non-Proliferation Treaty (NPT), which is designed to restrict nuclear weapons to a small group of major powers.
If North Korea creates a viable nuclear weapon, Japan would feel obliged to review its renunciation of the nuclear option, while Iran, already under sanctions for its nuclear programme, would feel emboldened to pursue its mastery of the nuclear cycle in defiance of United Nations sanctions.
But while the dangers are clear, the levers available to use against North Korea are getting weaker. Its technological progress in making a nuclear device is undeniable. As far as can be judged from the limited information available, creating a viable nuclear weapon is now only a question of time.
So what form will the "swift, credible and strong" response that awaits North Korea take? At the moment it can only be sanctions, the weapon of choice for diplomats these days, but one with a poor record of success. In other words, these threats are bluster, and the North Koreans know it.
International sanctions, where the ultimate goal is perceived to be regime change even if that purpose is not explicit, tend to bolster the government in power. A decade of sanctions against Iraq served to reinforce the regime of Saddam Hussein, whose cronies became rich on the back of smuggling and sanctions busting. The effect was to destroy the Iraqi middle class, either by impoverishment or exile, and causing the deaths, over the course of that decade, of many times more people than died in Dresden. The damage done to Iraqi society in those years helped to make post-invasion Iraq all but ungovernable.
The same impoverishment can be seen in Iran, where inflation is raging and the value of the rial is plummeting. But Iran has many years of experience of beating sanctions, and that country will not reach the promised point of "collapse" any time soon, if ever.
The effect has been the opposite: to speed up the enrichment of uranium, while apparently staying inside the threshold that would prompt US-Israeli bombing attacks on its nuclear facilities. President Mahmoud Ahmadinejad appears keen to explore a deal that might be on offer from Washington, but he has been slapped down by the supreme leader, Ayatollah Khamenei.
In Syria, a grab-bag of sanctions, including banning the import of luxury goods favoured by the wife of President Bashar Al Assad, were imposed by the US and the EU in the absence of more forceful action. Almost certainly no one imagined that the regime would still be in place today, almost two years after it began shooting protesters.
The challenge now is to find sanctions that will be smart, avoiding the national impoverishment of previous attempts. It is clear to all that, in a dictatorship such as North Korea, beggaring the people exerts no pressure on the regime, which will happily make the populace eat grass to meet its nuclear dreams.
On this page yesterday Mark Fitzpatrick, of the International Institute for Strategic Studies, argued that targeting North Korea's international financial connections would make the regime pay attention. In 2005, the US treasury ordered a freeze on the regime's accounts in a Macau bank, Banco Delta Asia. A similar action could unsettle the rule of the Kims.
Others have suggested a type of blockade, where foreign navies would have the right to inspect cargo ships heading for North Korea, though this would be meaningless without full Chinese support.
China holds the key to the North Korean conundrum. It does not want its ally to collapse and fall into the hands of US-allied South Korea. To that end, China supplies fuel, and allows North Korean workers to send home much-needed remittances. But it is showing impatience with the dynasty's refusal to stop nuclear tests.
For all the brave talk of "significant action", the levers remain the same: US-led financial sanctions and patient diplomacy with the Chinese, who alone have the means to bring the regime to its knees. There is, quite rightly, no Dresden option these days for North Korea. Nor should anyone contemplate an Iraq option. But the conclusion is that diplomats' tough talk has to be treated with deep scepticism.
On Twitter: @aphilps