Radical Islam has never been strong in Turkey, a country which is predominantly Muslim but has maintained a strict tradition of secularism since it was established in 1923.
By Ebru Dogan
BBC News Online
The general view is that the radicals are a small minority even within the Islamist community in Turkey.
Turkey's mostly Muslim population is unlikely to condone militancy
According to one analyst, Faik Bulut, there are about 100 religious associations of various sizes in Turkey, the most powerful of which are known as tariqats, but only six to 10 of them are believed to be militant.
He says it is precisely because the radicals could not get the support of the tariqats to overthrow the secular system that they have sought outside support - possibly from al-Qaeda.
Radical Islamists from Turkey are believed to have received ideological and military training in Iran after the 1979 revolution, although these ties are now acknowledged to have been severed.
They later joined the mujahideen in Afghanistan to fight against the Soviet invasion.
When they came back, they set up scattered local organisations under different names and went underground.
It is alleged that when the Kurdish insurgency started in Turkey in the mid-1980s, one of these radical groups, the Turkish Hezbollah was recruited to lead a "dirty war" against the insurgents.
WHO ARE IBDA-C?
Islamic Great Eastern Raiders' Front
Armed, underground Islamist network
Claim latest bomb attacks
Linked to bomb attacks on two synagogues
Leader is in prison facing death penalty
The group, which has no connection to the Shia Lebanese organisation of the same name, has been blamed for the disappearance of hundreds of Kurdish businessman and activists.
When the war petered out in the late 1990s, Turkish Hezbollah's torture chambers were exposed by the media and its leaders either killed or imprisoned by security forces.
Its supporters, and those of other organisations, went off to fight in Eritrea, Chechnya, Bosnia and Afghanistan.
Estimates of the numbers who joined the "global jihad" vary between 2,000 and 10,000.
The precise nature of their connection to al-Qaeda is hard to judge - many analysts believe that in most cases the connection has been "inspirational" rather than organic.
The suspects in the Istanbul synagogue attacks have variously been linked to the Turkish Hezbollah, a smaller group called IBDA-C or even smaller cells - no-one seems to know for sure.
Many people were dismayed to hear that they were Turks rather than foreign militants.
In the aftermath of 11 September, 2001, anti-US sentiment increased among Turks, who were overwhelmingly against the wars in Afghanistan and Iraq.
There was also a feeling that Muslims in general were being unfairly treated - but many Turks chose to see this in the context of big power politics, rather than a clash of civilisations.
Despite the anti-US sentiment, the public is not likely to condone radical Islamic militancy, because of its own experience of terrorism since the 1970s.
The question is where it will turn to look for the answers.
In the immediate aftermath of Thursday's attacks, some commentators argued for Turkey to stand up and be counted in President Bush's "war against terrorism".
They argued that only closer ties with the West, especially the EU, could provide security and stability in the longer term.
The last opinion polls before the bombings showed that almost 70% of the public favour joining the EU.
Others, however, have argued that the bombings were a direct result of the "EU dream" and the democratisation reforms passed to comply with the union's requirements.
They regard the one-year-old government's six reform packages as "harbingers of political instability" saying that they have weakened the security forces, prosecutors and courts, depriving them of the means to fight and deter terrorism.
The governing Justice and Development Party, which has its roots in Islamist movements, is adamant it will not be driven off course.
"Whatever message terrorism wants to give us, we are not taking it", said Prime Minister Recep Tayyip Erdogan.
"Indeed, we will trample on it."