Turkey's parliament has overwhelmingly approved a cross-border attack into northern Iraq in pursuit of Kurdish guerrillas – which would open another front in the war in Iraq.
The parliament in Ankara voted 507 to 19 in favour of ordering the army to launch an offensive across Turkey's south-eastern border in search of 3,500 PKK Turkish-Kurd rebels hiding in the mountains of Iraqi Kurdistan.
The Turkish move deepens the sense of crisis over Turkey's slow motion build-up towards an attack that has already helped propel the price of oil to $88 (£44) a barrel this week. It is becoming increasingly difficult for the government in Ankara to back away from its threats of military action without looking weak.
In Washington, President Bush spelled out US opposition to a Turkish invasion of northern Iraq. "We are making it very clear to Turkey that we don't think it is in their interest to send troops into Iraq," he said. Nato, of which Turkey is a member with the organisation's second biggest army, and the EU also urged restraint.
Mr Bush additionally called on Congress to drop plans for a resolution labelling as genocide the killing of 1.5 million Armenians in Turkey at the time of the First World War. The proposed resolution has raised hackles in Ankara. In a phrase likely to cause offence to Armenians Mr Bush said: "One thing Congress should not be doing is sorting out the historical record of the Ottoman Empire."
A Turkish army offensive would be unlikely to achieve anything against the PKK guerrillas who can easily disappear in the rugged mountain terrain of the Qandil mountains. They have dispersed their camps and ground troops would find it difficult to locate them – they will also be less vulnerable to air attacks. The Turks made no less than 24 attacks into Iraqi Kurdistan since 1984 with the permission of Saddam Hussein but without effect.
The prospect of a Turkish attack is a nightmare for the US. In the past, it has favoured the Turks over the Kurds but – during the present war in Iraq – it is very dependant on the five million Iraqi Kurds who are the only Iraqi community supporting the US occupation. The most effective units of the Iraqi army are also Kurdish and have been increasingly deployed outside Kurdistan.
Turkish leaders have stressed that a military attack into Iraq would not immediately follow the parliamentary vote. There are also some signs that Turkish threats are having an effect. The Iraqi prime minister Nouri al-Maliki called the Turkish prime minister Tayyip Erdogan just before the vote to say his government was determined to halt PPK "terrorist activities" and that the two nations needed to talk.
In reality, the Iraqi government in Baghdad has no control over Iraqi Kurdistan and what happens there will be decided by the Iraqi Kurds. They have so far proved averse to giving in to Turkish pressure and the Kurdish military forces – both the local peshmerga troops belonging to the quasi-independent Kurdistan Regional Government (KRG) and the Kurdish units in Iraqi army – are militarily far more effective than they used to be before 2003. If necessary, they could put up stern resistance to a Turkish attack.
Turkey could confine itself to moving troops into isolated mountain areas where there are only a few villages and making air strikes on supposed PKK locations. That might not lead to much response from the KRG leaders. But if the Turks advanced further, occupying towns such as Zakho close to the border, then there would be a much tougher military response.
The PKK has increased the number of its attacks inside Turkey and killed some 15 soldiers in the past two weeks, bringing to 200 the number of Turkish casualties this year.
The ambushes and bomb attacks have much greater political repercussions than they would appear to warrant because the AK moderate Islamist government is nervous of appearing unpatriotic and insufficiently supportive of the Turkish military. In April, the Turkish Chief of Staff, General Yasar Buyukanit said that a military operation was feasible and necessary.
Despite the US demand that there be no attack, Mr Erdogan is critical of the US saying at a rally in Istanbul last weekend: "Nobody can give us lessons on beyond-border operations. Did the US consult us when it entered Iraq from tens of thousands of thousands of kilometres away?"