LONDON, England (CNN) -- Who are the PKK?
PKK leader Abdullah Ocalan, pictured in 1992. Ocalan is currently serving a life sentence in a Turkish prison.
The Kurdistan Workers' Party (PKK) is a nationalist Kurdish guerrilla group that has been engaged in a campaign of violence against the Turkish state for more than two decades with the goal of establishing an autonomous Kurdish homeland.
The PKK accuse Turkey of oppressing Kurdish culture and suppressing Kurdish nationhood.
More than half of the world's Kurds (10 to 12 million) are estimated to live in Turkey, making up a majority in the country's south-eastern region. Iraq, Iran and Syria also have sizeable Kurdish minorities.
But the group is considered a terrorist organization by the U.S. and the European Union and is estimated to have been responsible for the deaths of more than 30,000 Turkish security force members and civilians, according to the U.S. State Department.
The groups founder Abdullah Ocalan was captured by Turkish commandos in 1998. Despite calling for a PKK cease-fire and peaceful negotiation following his capture, Ocalan was sentenced to death in 1999 following a trial condemned by the European Court of Human Rights.
However, his sentence was reduced to life imprisonment when Turkey abolished the death penalty in 2002. In the same year Ocalan's brother, Osman Ocalan, who had inherited leadership of the PKK, vowed to form a new group to campaign peacefully for Kurdish rights.
But the frequency of PKK terror attacks has steadily risen since 2004 and Turkey claims the U.S.-led invasion of Iraq and the country's subsequent instability following the overthrow of the Saddam Hussein regime in 2003 has enabled the PKK to regroup.
Why have the PKK made headlines recently?
Turkey accuses the PKK of launching attacks on Turkish targets from secret bases in the mountainous and semi-autonomous Kurdish region of northern Iraq. Earlier this year Turkey sent large contingents of soldiers, tanks, guns and armored personnel carriers to reinforce its frontier.
But following the deaths of 27 soldiers and 12 civilians in recent attacks, Turkish military leaders have urged the government to give them the green light to strike at PKK bases inside Iraq. One ambush took place on October 21 that left 12 Turkish troops dead and eight more missing.
The incident served to heighten calls from sections of Turkey's society to find a military solution to the situation and for Turkish troops to cross the border into northern Iraq.
What has been the response of Turkey?
Pressure has been mounting on Turkish Prime Minister Tayyip Erdogan to take definitive action against the PKK, which goes against his long term commitment to solve Turkey's Kurdish problem without involving the military.
However, calls by the country's generals to take military action were backed by the Turkish parliament's decision to sanction the use of force against the PKK operating in the Kurdish region in northern Iraq.
"Even though Turkey respects the sovereignty and unity of Iraq, her patience has come to an end and will not allow Iraqi soil to be used for terrorist activities," Gul told the Black Sea Economic Cooperation Organization on Thursday.
Western governments have urged restraint. Earlier this week, U.S. Secretary of State Condoleezza Rice, in a joint statement with British Foreign Secretary David Miliband, called for a conference to be held in Istanbul, Turkey, next month to discuss diplomatic solutions to the crisis.
The PKK did declare a unilateral cease-fire on Tuesday, raising some hopes that a Turkish incursion could be averted. But Turkish Foreign Minister Ali Babacan said after talks with Iraqi officials in Baghdad that a cease-fire "is something between two countries or two militaries, and not with a terrorist organization."
Since then there has been a military response. On Wednesday and Thursday, Turkish warplanes and helicopter gunships have attacked PKK positions within northern Iraq. CNN Turk, citing Turkish government and military sources, reported the activity and said it had been taking place since Sunday.
What would be the result of an invasion into northern Iraq?
There is concern in Iraq and expressed by the U.S. that cross-border action could plunge a region that has escaped the worst of the four-year-old Iraq war into conflict. The U.S. government is also worried that it would also jeopardize the major supply line to the U.S. military's 160,000 troops in Iraq.
Regional analysts are also skeptical that Turkey could defeat the PKK even with a full-scale offensive. The rugged and mountainous terrain of northern Iraq makes it ideal territory to conduct guerilla warfare and since the American-led invasion of Iraq, the PKK has had time and access to greater numbers of weapons.
Iraq's President Jalal Talabani, who is Kurdish, addressed the rising tensions with Turkey during a meeting with Kurdish regional leader Massoud Barzani in Irbil, the capital of Iraq's Kurdistan region at the beginning of the week. Talabani reiterated Iraq's demand that PKK rebels lay down their arms, and restated calls for a diplomatic solution. E-mail to a friend
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