If not now, when? This is the obvious and reasonable question of Iraqi Kurds seeking to exercise the right to self-determination – enshrined by the UN charter, though often ignored – in a referendum on Monday. They already enjoy a high degree of autonomy. They believe their key role in the fight against Islamic State demands recognition, giving them leverage over western powers; and that the alternative is continued, subordinate membership of a broken and divided Iraq, a century after the Sykes-Picot carve-up.

The response has been overwhelmingly negative. The rest of Iraq, the US, Iran, Turkey, Saudi Arabia, the UK, the EU and the Arab League all oppose the vote thanks to concerns ranging from Kurdish secessionism within their own borders and the furthering of ethnic divisions to the immense dangers it poses in a perilously unstable region – particularly given that voting covers the disputed territories the Kurds have gained in the fight against Isis. The US and others want the vote postponed, understandably. But “later” is almost as unsatisfactory an answer as “never” to Kurdish leader Masoud Barzani and his supporters – and that too is understandable.

The referendum is “not the end itself”, Mr Barzani told the Guardian: the near-certain victory will declare the desire for independence. There is room for negotiation. But Erbil will not go back to the table with a Baghdad that has no incentive to compromise, armed only with vague expressions of international goodwill. The Kurds want a UN-mandated solution, with a clear agenda, putting them on a path to their end goal through measures such as an enforceable deal on sharing oil revenues – as agreed but not maintained after the Iraq war. And their arguments have merit.

The vote has strengthened Mr Barzani’s position among his people; how much it will achieve for them is less clear. But denying their dream will come at a cost, too. There is still a little room and time for manoeuvre. It should be used, and with the utmost care.