By Leo Cendrowicz / Brussels

It is one of the most emblematic - and practical - achievements of the European Union: the Schengen Treaty, named after the Dutch town where it was signed, has gifted passport-free travel to Europeans, letting them glide unchecked across national frontiers once fiercely guarded by border guards.

Now, however, this signature feat of European integration could be rolled back. The Arab uprisings have created a surge of migrants fleeing towards Europe's southern rim, triggering a political rumpus. Last week, Italian Prime Minister Silvio Berlusconi and French President Nicolas Sarkozy jointly called for border controls to be reimposed, to cope with what they described as "exceptional difficulties." And on Wednesday, the European Commission declared that the governments involved in the Schengen zone - which allows passport-free travel between 22 participating E.U. Countries, plus Norway, Iceland and Switzerland - would now be able to set temporary border checks.

E.U. Home Affairs Commissioner Cecilia MalmstrÖm qualified the proposals as "a temporary re-introduction of limited internal border controls under very exceptional circumstances, such as where a part of the external border comes under heavy unexpected pressure." While she underlined the E.U.'s vocation as a haven for refugees and the benefits of targeted immigration to address labor shortages and declining birth rates, MalmstrÖm added that migration also has to be properly managed. "This means ensuring effective border control and the return of irregular migrants," she said.

Officials in Brussels admit that the scenes of refugees landing on the tiny Italian island of Lampedusa have stoked a febrile political climate that has piled pressure on the E.U. to act. Lampedusa, halfway between Europe and Africa, usually has a population of just 5,000, yet around 25,000 migrants from Tunisia and Libya have arrived on the island since January, all crammed into woefully inadequate tent camps. Warning last month about a "human tsunami," Berlusconi called on other E.U. countries to share the burden of dealing with the migrants. When the E.U. failed to respond, Italy granted the Tunisians temporary residency permits that allowed them, in principle, to travel across the Schengen zone. As the migrants then headed over the Alps, France reacted by rounding them up and sending them back. Commission officials said that with both countries pushing Schengen rules to the limit, it was better to review the system.

But critics say that the Commission's proposals are a sop to the surging anti-immigration mood in Europe, and an overreaction to a manageable phenomenon. "Twenty-five thousand stray Tunisians should not really pose a challenge to Europe's passport-free travel zone," says Roderick Parkes, who heads the Brussels office of the German Institute for International and Security Affairs. "It seems like a particularly low number, especially given that the bloc's member states coped with hundreds of thousands of immigrants from the Balkans in the mid-1990s." Indeed, during the 1992-95 war in Bosnia and Herzegovina, Germany gave temporary protection to 350,000 Bosnians while Austria gave permanent refuge to 66,000 and Sweden to 53,000.

There are also suggestions that Italy is indulging in political theater. Medical-aid group MÉdecins Sans FrontiÈres (MSF) accused Italy of deliberately exacerbating conditions for refugees in a bid to generate sympathy from other E.U. members. "The Italian authorities have responded in an ad-hoc and wholly inadequate manner despite knowing that the number of boats arriving always increases every summer and that the war in Libya would inevitably force many thousands more to flee," says Rolando Magnano, MSF head of mission in Italy.

Several northern European countries typically accept more asylum seekers than Italy, both proportionately and in overall numbers: while Italy took in just over 10,000 last year, France accepted 52,000 and Germany 49,000. Measured as a share of the population, Italy - with 40 asylum applications per million inhabitants - is not even in the top ten. As for the recent Libyan upheavals, most of the 650,000 people fleeing the violence have found hospitality in neighboring countries, primarily in Tunisia and Egypt. But many of them - like those who have landed in Italy - are foreign workers from countries like Somalia, Eritrea and Sudan, who are seeking a route back home.

Jean-Philippe Chauzy, director of communications for the Geneva-based International Organization for Migration (IOM), says these statistics show how the European debate has become twisted. "The economic downturn has increased resentment to migrants and a lack of tolerance, creating knee-jerk reactions," he says. "We have said from day one this is not a migrant tsunami, and that they just want to go home." As for the measures to reimpose border controls, Chauzy says not only will they create irritation for all other European travelers, but will probably fail. "The truth is that border controls are an ineffective way of stopping migrants. Migrants will just come in through other channels, like smuggling networks."

However, his blunt message is unlikely to be heard amid the alarmist rhetoric. The Schengen Treaty, for all its ability to ease travel across Europe, look set to be sacrificed - albeit temporarily - as governments cave in to popular anxiety about migrants.