In November 2003 Istanbul was hit by a terror attack that targeted two synagogues, a British bank and the British consulate, killing more than 50 people and injuring 700 others.
Turkish security officials arrested Loai al-Saqa, a Syrian man who was later convicted as the key perpetrator behind the bombings; he received the order to attack from Osama bin Laden, officials said. Another 48 terrorist suspects were arrested and later convicted in connection with the attacks -- a surprisingly high level of support that had security experts fear more bombings.
But nothing much happened since then.
Nevertheless, Turkish security officials have been increasingly worried recently; over the past few months, they on repeated occasions arrested terror suspects; in January they were even engaged in a 12-hour gunfight with an al-Qaida cell that left five people dead, including one police officer. While no information surfaced about their plans, the cell had stashed away weapons and explosives in great style.
Gareth Jenkins, a British journalist and analyst based in Turkey, told German newspaper Die Welt that an al-Qaida attack in Turkey may be imminent.
"There have been much more arrests in connection with al-Qaida," he said. "In my opinion, it is to be feared that there will be a larger attack in Turkey soon."
Earlier this month in Istanbul, police arrested 45 terror suspects during raids in eight neighborhoods in the European part of Turkey's largest city; security officials said the group had planned a "major attack" in Istanbul.
Synagogues could be targeted again, observers say, but also Western institutions, first and foremost of course the Incirlik Air Base, where the U.S. Air Force has at least 5,000 service members stationed, with several hundred British and Turkish personnel attached.
Nevertheless, attacks are hard to predict, mainly because the terror situation in Turkey is rather obscure.
"In Turkey, terrorism comes from several different currents," Berndt Georg Thamm, a terrorism expert in Berlin, told United Press International in a telephone interview. "For one, we have the Kurdish terrorism of the PKK; then there are Islamist groups, like the Islamic Jihad Union, which originated among the Turkic people in Central Asia, but enjoy support inside Turkey; and thirdly, and this can't be denied -- there is al-Qaida, which with small cells has gained a foothold in Turkey."
Turkey, with its 80 million Muslims at the border with Europe, plays an important role for militant Islamists determined to create a "global caliphate," Thamm added.
Circles critical of the pro-Islam government of Premier Recep Tayyip Erdogan say Ankara is pursuing a creeping Islamization of Turkey to demolish the tradition of constitutional separation of church and state first proclaimed by Mustafa Kemal Ataturk.
The secular elite have recently taken steps to stop that trend. On March 31 the Constitutional Court in Ankara decided to hear a case to outlaw Erdogan's Justice and Development Party and ban 71 of its senior party officials, including the premier, from politics for five years because they are threatening the constitution.
While that decision is highly controversial and was mainly linked to the government's decision to ease the head scarf ban at universities, some observers also fear that Erdogan's pro-Islam government makes it easier for terrorists to gain a foothold in Turkey.
"The current government has vowed to fight al-Qaida," Thamm told UPI. "But that doesn't mean that the struggle against Islamist currents outside Turkey's borders is led with the same intensity inside Turkey, where domestic groups are determined to undermine the country's separation of church and state."