Sea of Kalashnikovs

Stockpiles of Kalashnikov assault rifles have been discovered this week, and now Europe is scrambling to determine where the killers in the Paris terrorist attacks obtained their military-grade arms, amid mounting fears that the open-border Schengen zone could be flooded with AK-47s.

Four Kalashnikovs were reportedly found in a terror raid on an east Belgium apartment Thursday in which two suspects were killed after opening fire on police.

Just before the shootout at the Verviers apartment, Belgian newspapers were reporting that Amedy Coulibaly, the extremist who killed four people at a kosher supermarket in Paris, bought his automatic weapons for less than €5,000 at Gare du Midi in Brussels, the Belgian terminus for the Eurostar train.

A known trafficker had reportedly turned himself into the police, saying he had been in contact with Coulibaly in recent months and sold him a car - shortly after, authorities found documents and evidence of a weapons sale.

In France, meanwhile, police discovered a small suburban house recently rented by Coulibaly and used as a storage space for a weapons arsenal, which included three late-model Kalashnikov assault rifles and a rocket-propelled grenade launcher.

As investigators connect the dots to determine the original source of the weapons, experts say that it comes as no surprise that extremists, bent on launching attacks, were able to get their hands on military-style armaments.

"We know that they aren't on every street corner, but if someone wants to get a hold of one and has fairly good contacts in criminal circles, then it would not be an insurmountable problem at all," says Nic Marsh, a research fellow at the Peace Research Institute Oslo who is about to publish research on such arms trafficking in western Europe.

Underground networks

The guns were likely bought through drug traffickers or organized crime. The seller probably did not know the intended purpose and was not someone who specialized in supplying arms to political extremists.

"Most typically, former Yugoslavia is usually mentioned as the source, as weapons left over from the wars there fell into private hands. Someone might spend a few hundred euros on one in Bosnia, and then sell it for a few thousand somewhere, like France, Belgium or the Netherlands," Marsh said. "It's a business."

Still, though easy to obtain, they are not necessarily popular.

Automatic weapons are usually used for crimes such as bank robberies, but make up a very small percentage of the arms that are moving around Europe illegally - likely just because criminals prefer smaller guns which are easier to conceal, transport and use.

"We are talking about movement of probably tens, looking at how many appear to be available," Marsh says.

Even among those who have them, the rifles - which typically cost between €1,000 and €3,000 a piece - are very rarely used to kill, he said. The weapons can easily be transported to other European countries by truck.

Claude Moniquet, co-director of the European Strategic and Security Center in Brussels, agreed that the arms likely came from the Balkans. "They are easily imported from this region," he said.

Some weapons may also be coming from Libya, Gilles de Kerchove, the European Union's terrorism coordinator, told the AFP this week. “It's a real challenge but one can try to prevent them as much as possible without becoming a totalitarian society,” he said.

The UK is also wary of arms from those regions trickling in. "The member states of the European Union need to work together to put beyond use the vast numbers of weapons in the countries of the former Yugoslavia and disrupt the supply of weapons from other parts of the world, especially North Africa," Home secretary Theresa May told the House of Commons this week.

Czech origins

Police have not released details about the weapons used in the Paris attacks, or where they may have come from, other than to say that they arrived in France from abroad.

Before he took hostages at the supermarket, Coulibaly recorded a video in which an assault rifle is propped up beside him.

The weapon has been identified by experts as a Czech-made semiautomatic VZ-58 Compact, around for about 30 years on the underground market. The cost is about the same as a Kalashnikov.

"Often, this is the kind of gun which is bought and sold more than once, and it is not likely that someone recently drove it all of the way from Prague," said Marsh. "It will be very difficult to track exactly what the path has been."

Glenn McDonald, a senior researcher at the Geneva-based research group Small Arms Survey, says firearms trafficking has become a priority for the European Union, as well as France, amid high-profile cases of military weapons used in gang violence in the south. But, in general, there is little known about how many are in circulation, he says.

"Sometimes it is possible to look at seizure data, but it is an imperfect measure, so very little is known," says McDonald, who has researched gun use among the Italian mafia and in North America.

There are also questions about the financing for terrorist weaponry. While Coulibaly and the Kouachi brothers claimed to have received support from foreign terrorist organizations, reports have emerged that Coulibaly financed the weapons with a loan he took from French bank Cofidis in early December for €6,000 - tweaking his income on the application form so that he could qualify.

Calls for action

EU interior ministers and their western Balkan counterparts had agreed in December to a draft action plan on illicit trafficking of firearms between the EU and southeast Europe. A similar scheme between the EU and North Africa is also being considered.

But figures released recently, which imply France is awash with black market weapons - estimates of between 10 and 20 million have been circulating - are misleading, Marsh says.

Under current regulations some types of firearms, such as manually loaded shotguns, have to be registered upon purchase - usually done by the retailer. Owners do not have to declare all weapons in their possession, and in earlier years purchases were not required to be registered - meaning that many unregistered firearms in the country were purchased lawfully.

Meanwhile, a French Interior Ministry estimate of 4,000 military-style automatic firearms - a figure which dates back to 2010 - could be a false read.

"It is based completely on seizures, which fluctuate greatly year-to-year," Marsh says.

Illegal guns held in France are not widely used to kill people, he stressed. The number of gun-related homicides in France is not extreme - between 100 to 150 per year - one of the lowest firearm homicide rates in the world.