KEY POINTS:
A gentle breeze wrinkles the Bosphorus, the muezzin at the Blue Mosque calls the faithful to pray and old men sip tiny cups of grainy coffee in the spring sunshine.
This image of Istanbul is tempting for its timelessness. Yet beneath its reassuring surface is a country in the grip of powerful change.
Ask Turks where they think their country is or should be heading, and you will get many answers and all are likely to be tinged with anxiety.
Some fear Turkey is edging towards a religious state; others dread a backlash by the pro-secular, ultra-nationalist military, who staged three coups between 1960 and 1980; others fret about a civil war with the Kurdish minority.
"A few years from now, we don't know what's going to happen," says Mustafa Kemal, a British-educated businessman in his late forties. "It's anyone's guess."
A decade or so ago, what happened in Turkey could be regarded by much of the world as a sideshow. Not any more.
For one thing, this nation of 71 million people is increasingly prosperous, rivalling the newer members of the European Union in per-capita income. It also straddles the main export route for the oil-rich countries of the Caucasus. But most of all, Turkey plays the linchpin role in Washington and Brussels' vision of a Middle East that is tolerant, stable and democratic.
Many secular Turks worry about creeping Islamism under Prime Minister Recep Tayyip Erdogan, head of the Islamic-rooted Justice and Development Party (AKP), who has been in power for the last five years. Erdogan is expected toannounce this week if he will stand in next month's presidential elections.
Last Saturday, around 300,000 people took to the streets of Ankara, the capital, to set down a marker of support for secularism ahead of the vote. They rallied in front of the mausoleum of Kemal Ataturk, the revered founder of the Turkish republic, who set up a secular state, dividing religion from politics, after the collapse of the Ottoman empire in 1917.
On the eve of the rally, the current President, Ahmet Necdet Sezer, issued a sharp warning about the threat to secularism. A former Constitutional Court judge, Sezer has vetoed a record number of laws he deemed in violation of the secular constitution. He has also blocked Government efforts to appoint hundreds of reportedly Islamic-oriented candidates to key civil service jobs.
"Since the foundation of the republic, Turkey's political regime has never been under such threat," Sezer said. "For the first time in history, the fundamental values of the republic have been questioned and both domestic and foreign forces want Turkey to become a conservative Islamic model."
Prodded by the EU as a precondition for membership negotiations, Erdogan has pushed forward some important pro-democracy reforms, including curbs on powers of the military. As a result, the death penalty has been scrapped, tougher safeguards introduced against torture and headway made in women's rights and Kurdish culture.
But Erdogan has also tried to criminalise adultery - he backed down under EU pressure - appoint an Islamic central banker, taken steps to strengthen religious schools and spoken out against restrictions on wearing Islamic-style headscarves in government offices and the schoolroom. These, say critics, are signs that he will push an Islamic agenda if he becomes head of state, a charge that Erdogan denies.
Sezer steps down as President on May 16. His successor will be chosen by Parliament, which is dominated by AKP politicians.
Nationalism and ethnic frictions are other toxic additions to Turkey's problems.
In January, ethnic Armenian journalist Hrant Dink, who challenged the state position that the mass killings of Armenians by Turks in World War I was not genocide, was shot dead outside his office. An ultra-nationalist teenager has confessed to the killing - and the debate rages over whether the youth had links with networks within the state and security forces.
Even more troubling, though, is the prospect of fresh bloodshed over the Kurdish question. The Kurds live in an area straddling east and southeast Turkey, as well as smaller areas of Iraq, Iran and Syria. More than 30,000 people were killed in Turkey in the 1980s and 1990s in fighting between the Turkish Army and secessionist Kurdistan Workers' Party (PKK).
Strengthened by the establishment of a quasi-independent Kurdish entity in northern Iraq as a result of the war, the PKK has stepped up its operations across the border in Turkey, and Turkish troop deaths are now running at several a day.
Washington relied on stability in the Kurdish south, said Andrew McGregor of the Aberfoyle International Security Analysis in Canada.
"Southern Turkey's Incirlik Air Base is a crucial staging ground for US operations in Iraq and Afghanistan," he said.
"The US is unwilling to open a new front in northern Iraq, nor can it afford to lose its support from Iraq's Kurdish population. Kurds provide the most reliable units in the reformed Iraqi national Army."
In 2003, many in Turkey predicted the Iraq War would be disastrous for their country, sensing it would strengthen the PKK and bolster Kurdish demands on Turkish soil. Now the predictions appear to be coming true, with all the potential for driving a massive wedge between Ankara and Washington.
"It is the great under-reported story of the Iraq War," said Steven Cook, of the Council on Foreign Relations.
The war within
* Turkey's staunchly pro-secular President Ahmet Necdet Sezer warned at the weekend that the threat Islamic fundamentalism poses to the country's secular establishment has reached its highest level.
* His comments were directed at the Islamic-rooted Prime Minister Recep Tayyip Erdogan, who is expected this week to say if he is prepared to serve as president.
* Erdogan has tried to push through pro-Islamic laws and appointments, but has also given in to European Union demands and has denied having an anti-secular agenda.
* Parliament will elect a new president after Sezer stands down on May 16.
* Turkey's secularists fear that if Erdogan - or someone close to him - wins the presidency, the government will be able to implement an Islamic agenda without opposition.
* Kemal Ataturk, the founder of the Turkish republic, set up a secular state, dividing religion from politics, after the collapse of the Ottoman empire in 1917.
