Hardliners who stop at nothing
Hostage-taking, massacres, bombs in Turkish tourist resorts and attacks on Turkish consulates in Europe are part of a strategy to inspire fear and win an international profile for an organisation that even other Kurdish guerrilla groups are not quite comfortable with.
Turkey tries to dismiss the PKK as terrorist bandits, but that does not explain the success of this part- Marxist, part-nationalist, part-Islamic group, where it finds its financial support and who its foreign backers are. It appears to have been given at least transit facilities by hardline elements in Iran, an allegation denied by Iranian officials.
President Saddam Hussein of Iraq has given some aid to the PKK. But the PKK also maintains offices in northern Iraq, which is an anti- Saddam area controlled by Kurdish guerrillas, even though a Turkish- Iraqi Kurdish guerrilla offensive in October forced the PKK away from bases on the Iraqi-Turkish border.
The PKK's main backer has always been Syria. The PKK leader, Abdullah Ocalan, has been based in Damascus or the Syrian-controlled Bekaa Valley for more than a decade. Some speak of a weakening of Mr Ocalan's influence due to health and other problems, but the increasingly powerful chief of the PKK's military wing, Cemil Bayik, is also close to Syrian control.
But the key to Turkey's Kurdish problem is in Turkey itself. In the past nine years the insurgency has left 6,900 people dead, 1,015 of whom have died since May, when the collapse of a unilateral guerrilla truce plunged the south-east into its worst bout of bloodshed yet.
The rebels are a powerful and feared symbol of a national struggle for many of Turkey's 12 million Kurds.
They have filled a vacuum cleared for them by the Turkish security forces, who have refused to allow the emergence of a moderate Kurdish nationalist political centre.
IoS exclusive: MI5 'tried to recruit' Woolwich attack suspect Michael Adebolajo
French soldier stabbed in the neck in Paris
EDL marches on Newcastle as attacks on Muslims increase tenfold in the wake of Woolwich machete attack which killed Drummer Lee Rigby
Fallen angel: Winona Ryder on bouncing back from her decade in the wilderness
Hurricane season fears as warning satellite fails
BMF is the UK’s biggest and best loved outdoor fitness classes
Find out what The Independent's resident travel expert has to say about one of the most beautiful small cities in the world
Nook is donating eReaders to volunteers at high-need schools and participating in exclusive events throughout the campaign.
Get the latest on The Evening Standard's campaign to get London's children reading.
Win anything from gadgets to five-star holidays on our competitions and offers page.