Along with fears of Islamic terrorism, the July 7 attacks in London - and new explosions Thursday in the British capital - are renewing European debates over immigration and asylum laws, and how to treat roughly 40 million foreigners living in the region. It is too early to say what the fallout will be. But some human rights groups fear the emergence of a fortress Europe with closed borders to foreigners. Others disagree.
The London bombings have triggered soul searching about how to deal with second-generation immigrants in Europe, since those suspected of the July 7 attacks were all British citizens. But they are also renewing a long-simmering debate about how to screen and crack down on would-be first-generation immigrants as well.
Europe has long had conflicted feelings toward immigration. Some Europeans believe the region needs more foreign workers, while nationalist groups argue foreigners are taking jobs away from locals.
Now, a new factor has entered into the immigration equation: Fears of foreign-born terrorists.
Those fears surfaced after the September 11th, 2001 attacks in the United States. Islamist terrorism has arrived in Europe as well, with 2004 bombings in Madrid, and this month's attacks in London.
Patrick Delouvin is an immigration specialist at Amnesty International in France. He argues those terrorism fears have helped usher in tougher asylum and immigration measures in Europe.
"Definitely, after the September 11th attacks, the Europeans thought about restricting immigration, restricting asylum," he said. "They have had many meetings to talk about it. And they began to take measures to restrict immigration on European territories. At the beginning for 15 states, but now for 25 [EU member] states."
Mr. Delouvin says the French government has stepped up border controls to winnow out illegal immigrants and questionable asylum seekers. It is also working closely with foreign governments and airlines to tighten those controls.
At the Charles de Gaulle airport outside Paris, for example, the numbers of people allowed to apply for asylum in France dropped from 10,000 in 2001 to only 2,500 last year. Five years ago, Mr. Delouvin says, 700,000 asylum seekers arrived in the European Union. Last year, less than half that number were admitted.
Sergio Carrera, a justice and home affairs specialist at the Center for European Policy Studies in Brussels, says tougher asylum and immigration laws are part of a larger arsenal of security measures the European Union has been discussing to fight terrorism.
Some of the proposed measures, he says, such as biometric passports and data bases to track questionable foreigners have been criticized for possibly violating human rights and personal freedom statutes of the European Union.
"They [the new security measures] are sold because they intend to fight against terrorism," Mr. Carrera said. "They are intended to bring more security. They are going to prevent these things [terrorism] from happening again. But for me, its not really clear the extent to which these measures are going to be more effective. The extent to which these measures are going to improve security and insure liberty within the European Union."
But the latest generation of terrorists includes many Europeans.
For example, Zacharias Massaoui, the first person prosecuted in relation to the September 11th hijackings, had French nationality. The man accused of killing film-maker Theo Van Gogh last year was Dutch.
Even Egyptian Mohammed Atta, who studied in Germany and was considered the ringleader in the September 11th attacks, may not have triggered suspicion by European immigration authorities. That, at least, is the assessment of Rainer Muenz, a demography specialist at the Hamburg Institute of International Economics.
"Just think about Mohammed Atta," he said. "Someone who was studying at a technical university, coming from a middle-class background from an Arab country. If we had discussed him five years ago, we would have both agreed with many other people that Atta is exactly the type of migrant we will need in the future."
Mr. Muenz says its too early to say whether the London attacks will translate into tougher European-wide immigration policies. In the case of Spain, the effect was the opposite. A year after the Madrid bombings, the leftist government of Prime Minister Jose Luis Rodriguez Zapatero allowed hundreds of thousands of illegal immigrants to apply for legal status.
"In the Spanish case, the effect was not in the direction you would expect, based on conventional wisdom - that they would be more serious on cracking down on immigrants," he said. "There has been the largest regularization campaign in Spanish history. You could say this has helped bring these people to the fore and make them more visible. It is a soft strategy."
Other analysts doubt tougher immigration and asylum laws have much to do with new European fears of terrorism. French immigration expert Catherine de Wenden believes tougher asylum policies, for example, are in response to European concerns about bogus applicants.
Ms. de Wenden is an immigration expert at the Center for International Studies and Research in Paris. She says more people from poor countries are seeking political asylum, when in fact they are economic refugees - and would be rejected as such under European immigration laws.
For these and other reasons, Mrs. de Wenden believes that terrorist attacks have not had a direct impact on immigration flows. She says the profile of a terrorist is not that of a foreigner crossing the Straits of Gibraltar to Spain - as is the case of many illegal immigrants arriving in Europe. Rather, she says, many terrorists are well installed in the country they live in - and they have their immigration papers in order.