NATO leaders appear to attach greater importance to a Russian warplane’s brief entry at the weekend into Turkish airspace than to their professed aim of destroying Islamic State (Isis).

This is the unavoidable conclusion to be drawn from the overexcited comments by politicians in Nato member states and the cold war alliance’s secretary-general Jens Stoltenberg.

Stoltenberg asserted yesterday that Saturday’s incursion “does not look like an accident,” accusing Russia of failure to produce a “real explanation.”

Moscow, as a matter of record, had blamed the brief violation on bad weather.

The Nato secretary-general observed later that it is “unacceptable to violate the airspace of another country.”

The bizarre reality is that those complaining most loudly about a regrettable but short-lived infringement of Turkey’s airspace are systematically violating Syria’s, thereby flouting international law at will.

Russia, which is co-ordinating its air raids with the Syrian armed forces, is in the country with the full agreement of the Bashar al-Assad government.

Its planes are already flying two or three times as many daily missions as the much-hyped “anti-Isis coalition” put together by Washington.

It is reasonable to expect a major advance by the Syrian army against Isis and its allies in the near future to benefit from disruption of their defences, command structures and supply lines by the Russian bombing raids.

If the US, Turkey and their allies were serious about their designation of Isis as prime enemy, this ought to give them cause for celebration, but their demands for Russia to halt its assistance to Damascus invite another assessment.

US Defence Secretary Ash Carter insists that Moscow contact Washington for another meeting to avoid the chance of accidents over Syria between planes there by agreement and others by assertion of imperial arrogance.

The issue is likely to be a major item at a Nato meeting in Brussels this week.

A more serious question that Nato ought to have broached by now is how Isis developed into a lavishly funded and well-organised military force capable of occupying extensive tracts of land, defending them and administering them according to its brutal and obscurantist ideology.

Why has Nato not convened meetings asking why its allies Saudi Arabia, Qatar, Kuwait and the United Arab Emirates have permitted donations and volunteers to make their way to Iraq and Syria?

Why has Turkey assisted Isis financially by accepting the terrorist group’s fuel exports from oilfields it has occupied in Iraq and Syria?

Ankara’s collusion in allowing jihadists from around 80 countries to travel across its border into Syria to join Isis, the Nusra Front and other terrorist outfits contrasts with its reluctance to allow arms and reinforcements to help the heroic Kurdish defenders of the Syrian town of Kobane.

The US provided air support to the YPG Kurdish fighters at Kobane to the intense displeasure of Ankara, which had previously forbidden the Syrian air force from doing so.

Yet Washington plays along with Turkish President Recep Tayyip Erdogan’s designation of his country’s Kurdistan Workers’ Party (PKK) as a terrorist organisation when YPG and PKK are essentially the same body.

The main drawback to the US and its allies prioritising the campaign against Isis is their insistence that they, rather than the Syrian people, should decide Syria’s form of government and who should lead it.

Until they modify this imperialist mindset they will be more a hindrance than an asset to the campaign to defeat the Isis death cult.