Gareth Jenkins looks at the fall-out from the Turkish incursion against Kurdish rebels in northern Iraq Backed by helicopter gunships and F-16 fighter bombers, Turkish commandos attacked bases of the Kurdistan Workers' Party (PKK) in northern Iraq 21 February in Turkey's first major ground operation into the country in more than a decade. The Turkish army appears to have met with fierce resistance. No independent figures are available for casualties. The Turkish General Staff released a statement which claimed that in four days of fighting it had killed 153 PKK militants with a loss of 20 members of the Turkish security forces. However, many of the PKK casualties were assumed to have been killed in air strikes or artillery bombardments. The figure is unlikely to be precise. Turkish media claimed that up to 10,000 troops backed by tanks crossed the border in a full-scale invasion. Although the Turkish military has still not released details of the size of the operation, both US-led Coalition forces in Baghdad, who have the area under constant surveillance, and Iraqi Kurds on the ground in northern Iraq reported that the incursion was much smaller, involving only a few hundred soldiers. The main target of the incursion appears to have been the PKK's forward bases in the mountains along Iraq's border with Turkey. The PKK is believed to have over 3,000 militants under arms in northern Iraq, many of them waiting out the winter before the spring thaw melts the snow in the mountain and enables them to infiltrate back into Turkey to resume the organisation's 23-year-old insurgency. Not even the Turkish military expects the current operation to eradicate the PKK presence in northern Iraq. PKK militants are highly mobile and lightly armed, their bases usually little more than a few scattered huts or caves. In the 1990s, a series of large- scale Turkish incursions into northern Iraq, sometimes involving up to 50,000 troops, inflicted only temporary damage. Most of the PKK militants simply withdrew ahead of the advancing Turkish troops, leaving them to destroy whatever stocks and arms caches they could find. Once the troops withdrew, the PKK militants simply returned to their bases to rebuild, restock and regroup. But the latest Turkish military incursion will nevertheless have come as a psychological blow to the PKK. Until relatively recently, the US had repeatedly warned Turkey not to stage any cross-border military operations for fear of destabilising a region which has suffered less than any other in Iraq from the carnage and chaos that followed the overthrow of Saddam Hussein in 2003. However, following an upsurge in PKK attacks in Turkey in autumn last year, Washington finally gave the green light for Turkey to conduct air strikes against PKK positions in northern Iraq, which started in early December last year. In recent weeks, the PKK had become increasingly concerned that the US might also be prepared to allow Turkey to stage a limited ground operation but it had not expected a major attack until the spring. As a result, last week's incursion will have come not only as a shock but a reminder that it is no longer safe even in Iraq. But the danger for Ankara is that military success against the PKK may strengthen cross-border Kurdish solidarity and further alienate Turkey's already restive Kurdish minority. In addition to its insurgency against the Turkish state, the PKK has an unenviable record of attacking its fellow Kurds. Ultimately its continued presence in northern Iraq is also a challenge to the political authority of the Kurdistan Regional Government (KRG). So far, both the Iraqi government in Baghdad and the KRG in Arbil have issued relatively restrained public comments on the Turkish incursion, focussing primarily on calls for the operation to be as limited as possible in scope and duration. But, although it may play well with Turkish nationalists, the Turkish claim to have killed large numbers of PKK militants has resulted even in its opponents rallying behind the organisation. "We don't like the PKK," said a member of a rival Kurdish organisation on condition of anonymity. "But when it comes to Kurds being bombed and attacked by Turks then we are prepared to forget our differences and give them all of our support." The incursion has also been bitterly opposed by many Kurds inside Turkey. On Saturday night, PKK supporters in Istanbul torched vehicles to protest against the operation. On Monday, an estimated 20,000 Kurds marched through the southeastern city of Diyarbakir calling not only for an end to the incursion but, for the first time, on Jalal Talabani, the ethnic Kurdish Iraqi president, to come to the PKK's aid. Several carried banners in Kurdish which read: "Wake up, Talabani! We will be lunch and you will be dinner."