By PATRICK COCKBURN
Several thousand Turkish troops crossed into northern Iraq in pursuit of Kurdish guerrillas early Wednesday. The incursion, though limited in scope, gives the crisis in Iraq a new twist.
"It is not a major offensive and the number of troops is not in the tens of thousands," said an official in south-east Turkey where there has recently been an upsurge in activity by the Kurdistan Workers Party (PKK) Turkish Kurd guerrillas.
Nevertheless, the US will be worried that its entanglement in Iraq is about to become even more complicated if American troops and aircraft are asked to counter even a limited Turkish assault.
The US military said it could not confirm the reports but was "very concerned". Turkey has been threatening an attack into Iraqi Kurdistan in recent weeks and, last weekend, Robert Gates, the US Defense Secretary, warned Ankara against a foray into northern Iraq.
The PKK have several base areas in Iraqi Kurdistan, including the rugged Kandil mountains on the Iranian border, a natural fortress providing ideal terrain for guerrillas. Even if the Turks did send a large military force into northern Iraq, as it did last in 1997, it would be difficult to locate, still less destroy, the PKK.
The scale of PKK activity in Kurdish-populated areas of south-eastern Turkey is still limited but the Turkish army and moderate Islamic government have threatened retaliation. Both have a motive for demonstrating their patriotic credentials in the approach to parliamentary elections this summer.
In a sign of the limited communication between the Turkish government and military, the Foreign Minister, Abdullah Gul, denied that a cross-border operation had taken place. "There is no such thing, no entry to another country," Mr Gul said. "If such a thing happens we would announce it."
The Iraqi government was also eager to play down reports of an attack, despite statements by Turkish military officials. Iraq's Foreign Minister, Hoshyar Zebari, said there had been "no major operations" by Turkey though there had been a build-up of Turkish troops.
Turkey also has an incentive to put pressure on the Iraqi government and the Kurdistan regional government because a referendum is to be held on the future of the oil province of Kirkuk before the end of this year.
Patrick Cockburn is the author of 'The Occupation: War, resistance and daily life in Iraq', a finalist for the National Book Critics' Circle Award for best non-fiction book of 2006.