Frattini told journalists in Brussels yesterday that joining by the target date of October 2007 would depend on each of the 10 having the necessary Schengen-related data exchange and information systems fully working.
Schengen is a border-control system under which incoming travelers are checked by officials only at an outer frontier of the EU, and then have freedom to cross all the other national borders in the Schengen states.
This means, for instance, that a Ukrainian family traveling west by car would be checked by Polish officials at the border. If their papers are determined to be in order, they could drive unhindered across nearly all Western Europe.
"If you travel around in Western Europe, you will discover that you can travel to Germany, to the Netherlands, to Belgium, to Italy, [and elsewhere], and there is nobody to ask for your passport," explained Alfred Pypers, an analyst with the Netherlands Institute of International Relations.
Present EU members Britain and Ireland have so far declined to join the full Schengen system, preferring to keep control over cross-border flows a national responsibility. However, Norway and Iceland, two countries that are not EU members, are in Schengen.
The intention to expand Schengen so drastically is causing some worries among the older EU member states, like Germany and the Netherlands, which see themselves as the likely end destination of many purported tourists who are actually illegal immigrants, as well as criminals.
"We [in the old EU states] have some concern about expanding the Schengen system, and we require that countries like the Czech Republic and Poland will take care to properly manage the external border," Pypers said.
It's a massive task, to control international criminality, the smuggling of drugs, human trafficking, and illegal immigration, at only the outer frontier posts.
And the more so because in the north and east, the new members like Poland, Slovakia, and Hungary have few resources. To the southeast and southwest, outer border countries like Greece, Italy, and Spain have an almost impossible task in controlling their sea borders.
Peter Zervakis, an analyst with the Bertelsmann Foundation in Germany, said this "one chance to win" aspect is the Achilles' heel of the Schengen system.
He said there are two schools of thought on how to proceed to improve the system. The first foresees more police-type measures, including agreements with the EU's new eastern neighbors to deal with potential illegal immigrants before they reach EU soil, a sort of "forward control."
"Interior ministries, including those of the Schengen countries, are counting on increased security, meaning more border police, strengthened border crossing procedures and forward control; and negotiations are going on in the EU budget process [to provide more money] for those countries which are the hardest hit, those which have outer borders," Zervakis said.
Zervakis said the eventual outcome of these security measures may well be the emergence of a separate EU border-patrol service, to physically strengthen national efforts to control movement across outer borders. It is an idea that had already been discussed at some length, and is referred to in the union's draft constitution.
The second school of thought is that the real solution to the problem lies not in having more men in jeeps and helicopters along the borders, but instead in combating the underlying social causes for the mass movement of people into Europe.
"Social problems must be tackled preventively," Zervakis said. "This means the EU must undertake steps in the affected countries, in Africa, also among the eastern neighbors, like Belarus, Ukraine, and others so as to solve the problems there, at home, so that they are not imported [to us]."
This second way of tackling the problem, if it prevails, could therefore bring some economic benefits to the eastern countries that have become the EU's new neighbors.