From Athens and Warsaw in the east to London and Lisbon in the west, Europe is reacting to last week's bombings in Spain by vowing to keep terrorists at bay.
Rail and underground networks across the Continent are bristling with heightened security following the Thursday bombings on Spanish commuter trains that killed 200. Greece has called in NATO to help bolster security for the August Olympic games, while Portugal is multiplying measures to protect its own summer sporting showcase - the Euro 2004 soccer championships, as the implications of a first Al Qaeda-linked terror attack on European soil hits home.
The EU as a whole is trying to present a united front, calling an emergency counterterrorism meeting for Friday, ahead of a summit on the subject next week, and suggesting the appointment of a special commissioner to pull together a hitherto disparate European antiterror effort.
Some countries feel more vulnerable than others. Those in the front line of the Iraq campaign have noticed a chilling sequence to recent terror attacks: Britons killed in Istanbul, Italians and Bulgarians in Iraq, and now Spaniards in Madrid.
"There is a general appreciation of the fact that Poland is now a target of terrorists," says Radek Sikorski, a former Polish defense minister. "There is a nervousness about what might happen, and it is justified."
Britain responded to the Madrid bombings by dispatching plain clothes police to the London Underground, where a new poster campaign warning of the dangers of unattended luggage greeted alert-weary Londoners; a rash of suspicious packages sent to several embassies only added to the jittery mood in a city which police admit is a top target for terrorists.
"As the prime minister and home secretary have said, there is an inevitability that some sort of attack will get through," admitted Metropolitan Police commissioner Sir John Stevens.
Even countries that opposed the Iraq war like France and Germany are alive to the new threat.
Dana Allin, an expert in European security and defense policy at Institute for International Strategic Studies in London, says that while it may appear that Al Qaeda and its associates are picking off coalition targets, "that does not for one minute mean that others are safe."
"The French for example know they are targets," Dr. Allin says. France may not have backed the Iraq war, but it has cooperated in fighting Islamic militants in north Africa, which has become a new focus in the antiterror fight since the detention of three Moroccans in connection with the Spanish bombings.
Germany, too, opposed the Iraq war, but its involvement in Afghanistan and its law enforcement efforts at home have put it in the firing line. "That's why we have to be prepared for Al Qaeda possibly taking aim at us as well," Bavarian Interior Minister Guenther Beckstein said in a radio interview, as security was enhanced at major rail hubs.
Though the Madrid attacks were the first in Western Europe since Sept. 11, Europe is no stranger to terror attacks. Britain's decades-long struggle with the IRA and France's battle with Algerian extremists have left agencies with useful experience.
"Britain's experiences with the IRA are in many cases applicable to the struggle against Islamic extremism," says Charles Shoebridge, a security expert and former counterterrorism intelligence officer. "The public is already aware of a need for vigilance, and the intelligence systems are in place to enable, for example, surveillance, telephone intercepts, and informant penetration of the target organization.
"But we still have to run to catch up - the UK sorely neglected Islamic extremism before Sept. 11," he says.
Catching up may involve closer EU collaboration, but the Continent is still a fragmented map of dozens of countries with competing law enforcement agencies that make joint action difficult.
Some countries have yet to enact agreed legislation creating an EU-wide arrest warrant, leaving the antiterror struggle at the mercy of frustrating extradition procedures. The Europol antiterror unit is still considered an additional, optional resource rather than the default destination for vital intelligence.
"It's a difficult job," says Allin. "Europe has a very difficult task. It's not one country and there's a certain [paranoia] about data protection. It makes it harder for them to work together."
Some have called for a new continent-wide agency - a sort of European CIA - to get national teams working better together. But others say this would be highly problematic given that some national security agencies have difficulties working with their own police forces, let alone someone else's.
• Reporter Andreas Tzortzis contributed from Berlin.