Why is Turkey threatening to launch military strikes into northern Iraq?
Because Kurdish guerrillas from the PKK use the mountains of northern Iraq as bases for cross-border raids on Turkey. No one has effective control over northern Iraq and this lawless area provides a convenient haven for the PKK. Its fighters have killed 15 Turkish soldiers and 12 civilians this month alone.
Who are the PKK?
Founded in 1978, the Kurdistan Workers' Party or PKK wants a separate state for the Kurdish population of south-eastern Turkey. It took up arms in 1984, sparking a guerrilla war which has claimed 37,000 lives. Both America and the EU consider the PKK a terrorist organisation.
Is Iraq helping Turkey against the PKK?
Officially, the Baghdad government proclaims sympathy for Turkey and says that it will deal with any PKK guerrillas on its territory. In fact, the PKK has strong support from Iraq's Kurdish population. Baghdad has no real control over northern Iraq, which is autonomous and run by two factions – the Kurdish Democratic Party (KDP) and the Patriotic Union of Kurdistan (PUK). Turkey believes that elements of the PUK are allied to the PKK. Turkey accuses the authorities of tolerating the PKK.
What are the possible consequences of a Turkish raid?
America fears it would create more chaos in Iraq. So far, Iraq's Kurdish region has been the only reasonably stable area of the entire country. There are even efforts to attract tourists and investment. Moreover, it would be a visible symbol of America's failure to stabilise Iraq since toppling Saddam Hussein in 2003. Any Turkish operation would also shatter the authority of the government in Baghdad on which America has pinned its hopes for a democratic Iraq.
What is America's position?
America has urged Turkey to show restraint and give the Iraqi authorities time to deal with the PKK. Washington does not want Turkey to take any action that might cause more bloodshed in Iraq. Instead, it has tried to promote security co-operation between the neighbours. Last month, Turkey and Iraq signed an agreement under which Baghdad pledged to close down the PKK. But Iraq refused Turkey's request for permission to carry out a cross-border operation.
What are the pressures on Turkey's government?
Recep Tayyip Erdogan, Turkey's prime minister, finds himself under pressure from all sides. America, a close and vital ally, wants him to stay out of northern Iraq. Thanks to the PKK's recent attacks, Turkish public opinion wants strong action. Anti-American feeling has risen sharply in Turkey, making the situation still more difficult. A powerful Congressional committee has inflamed feelings still further by declaring Turkey's mass killing of Armenians during the Ottoman era a "genocide".
What might Turkey do?
Mr Erdogan could order a large-scale invasion of northern Iraq and occupy a buffer zone to shield against PKK incursions. Although the most effective option, this would also risk chaos in Iraq and American counter-measures. Turkey's army could carry out raids on guerrilla bases, possibly accompanied by air strikes. The danger is that limited strikes would be ineffective but they would minimise international protest.