If Turkey’s Army is to be taken at face value, it has 140,000 troops and substantial detachments of heavy armour massed along the country’s southeastern border. It has the Government’s approval in principle for cross-border incursions into Kurdish Iraq. It awaits only parliamentary approval, which could be given as early as today, before launching such operations. And it has ample justification in the form of a 30-year running battle with separatist fighters of the Kurdis-tan Workers’ Party (PKK), which has cost 30,000 lives, including those of 13 Turkish soldiers gunned down on their own soil on Sunday.

Yesterday, Recep Tayyip Erdogan, the Prime Minister, confirmed that “preparations for parliamentary authorisation” had begun. He may feel that political and military pressure for a strike on PKK bases in Iraq has become irresistible; it is certainly more intense than at any time since 1995. Even so, he must resist it at all costs.

Mr Erdogan has described his country’s struggle with the PKK as a counter-terrorism campaign with “the same legitimacy for Turkey as it has for the US, Spain or the United Kingdom”. It is true that the Kurdish separatists’ arcane brand of Marxism-Leninism is an ideology almost as extreme, in its way, as that of the al-Qaeda groups that the secular West is battling against worldwide. The PKK is also listed as a terrorist organisation by both the US and the EU. But Turkey’s conflict with the PKK is about territory as well as ideology, and the territory in question is an enclave within an otherwise relatively peaceful and prosperous region of Iraq.

Any significant Turkish military operation in Kurdish Iraq would bring turmoil to the only sector of the country spared large-scale violence since the allied invasion four years ago. It would put at risk Turkey’s strategic alliance with the US, which ensures American access to the vital Incirlik air base but also constitutes Turkey’s single most important source of support in its efforts to win EU accession. It would jeopardise what international support Turkey enjoys in its struggle with Kurdish separatism, and would expose Turkish forces to far greater risks than they now face, not least because of the danger of rival Kurdish factions uniting against them.

Last month Iraq agreed with Turkey to work towards shutting down PKK bases in northern Iraq. The deal is flawed, chiefly because of a perception among Iraq’s Kurds that they have not been consulted. The likelihood, as a result, is that they will attempt to sabotage rather than enforce it. But it explicitly, and rightly, ruled out Turkish cross-border incursions. Ankara had claimed a right to pursue suspected terrorists wherever they fled, but legitimising armed raids across international borders would be an incendiary recipe. It is no more justified for Turkey in Iraq than for Russia in Georgia, where Moscow has courted international opprobrium with cross-border attacks against Chechen terrorists.

Before the Iraq war, Kurdish separatism was a fading force. The PKK has exploited Iraq’s agonies to attack Turkish targets again with little fear of cross-border reprisals. Turkey’s demands for action are understandable, but it must show maturity and forbearance. In return Iraq, with US support if necessary, must deliver on its pledges to deny the PKK a haven. A new conflict in the Middle East would serve no one’s interests.