Hostile moves by neighbouring governments to blockade and isolate the Kurds of northern Iraq in punishment for this week’s vote for independence require a robust response by Britain and the international community. Despite the historical betrayals of the western powers, the Kurds have proven loyal and valuable allies in the struggle against Islamic State and the former dictatorship of Saddam Hussein. Now is time to settle the debt.

With the official results of the referendum called by Masoud Barzani’s Kurdistan regional government (KRG) due on Wednesday, it is already clear an overwhelming majority backed independence. This outcome was never in doubt. It represents the partial culmination of a dream of self-determination and self-rule nurtured by generations of Kurds since the arbitrary Anglo-French carve-up of the Ottoman empire at the close of the first world war left them dispersed, stateless and homeless.

Barzani on the Kurdish referendum: 'We refuse to be subordinates' Read more

What is surprising, and dismaying, is the extraordinary display of unanimity exhibited by the world’s most powerful governments in opposing Kurdish independence. When before in the modern era have the US, the EU, Russia and China, plus the Arab League, Iraq, Iran, Syria and Turkey all agreed on anything? Boris Johnson and Britain’s Foreign Office are part of this too cosy consensus. They argue, like the others, that Kurdish aspirations fuel instability in a volatile region.

As always when dealing with the Kurds, the self-interest of outside actors obscures the vision of a better future. Their short-term focus is on defeating Isis and Islamist terrorism in general. Their longer-term interest, particularly the US and Russia, is in shaping the balance of power and advantage in a post-Arab spring, post-Syria Middle East. In the great powers’ geopolitical playbook, the Kurds have their uses. But their ideas of nationhood are a nuisance.

The limitations of this blinkered outlook are becoming apparent as Britain and its allies find themselves on the wrong side of a rapidly developing confrontation between Barzani’s government and its immediate neighbours, principally Iraq, Iran and Turkey. The KRG is not the cause of this upsurge in tensions. It has just conducted a long-delayed, highly successful, transparent and inclusive democratic exercise in a region not renowned for grassroots consultation.

The source of tension is external. Take, for example, the behaviour of Recep Tayyip Erdoğan, Turkey’s president. Erdoğan has spent the period since June, 2015 – when he almost lost power due, in part, to the success of a pro-Kurdish party – attacking the Kurdish minority populations in south-east Turkey and northern Syria, curbing democratic freedoms and purging tens of thousands of supposed fifth columnists. His neo-Islamist regime has cut cooperation with Nato and blackmailed the EU over Syrian refugees.

Erdoğan has proved himself no friend of Britain or Europe, or of western values. Now this same posturing bully is threatening to starve out the Iraqi Kurds and block their oil exports for having the temerity to try to direct their own future – and Britain is in his camp.

“[They] will be left in the lurch when we start imposing sanctions. It will be over when we close the oil taps, all [their] revenues will vanish, and they will not be able to find food when our trucks stop going to northern Iraq,” Erdoğan warned.

In opposing the referendum, Britain also finds itself in bed with Iran, which has a long, ignoble history of oppressing its Kurdish minority. To mark its displeasure over the possible knock-on effects, Tehran sent fighter jets screaming menacingly over Kurdish areas of western Iran on Tuesday. The “ethnic and sectarian war” predicted by Erdoğan is also rendered a more likely prospect by this week’s joint Turkey-Iraq military exercises along the KRG’s border and moves to shut down airports and trade routes.

'The best day of my life': Iraqi Kurds vote in independence referendum Read more

Barzani is meanwhile facing a predictable barrage of condemnation from Baghdad, where successive Iranian-backed, Shia-led governments have fiercely opposed Kurdish self-determination. Iraqi Shia militias are reportedly ready to march on Kurd-controlled Kirkuk. But if fighting breaks out, it will be the fault not of the KRG but of its hostile, insecure neighbours and of complacent, unimaginative western leaders.

In a report published in 2015, the Commons foreign affairs committee was clear where Britain’s loyalties lie. “The UK is fortunate to have in such a volatile part of the world a partner as relatively moderate, pragmatic, stable, democratic, secular and reflexively pro-western as the KRG,” it said. Maintaining the KRG as a “haven of tolerance and stability”, not least in its approach to women’s rights and humanitarian issues, and as an ally against extremist forces, was of critical importance.

Saddam tried to crush the Kurds of northern Iraq in 1991, in the wake of the first Gulf war. Britain and its partners responded effectively with safe havens and a no-fly zone. A determined, principled stand is once again required to uphold the Kurds’ democratic rights.

• Simon Tisdall is an assistant editor of the Guardian and a foreign affairs columnist