Despite strict regulations on firearm ownership, gun use in Europe has surged in the past few years, driven in part by in part by fear instilled by terrorist attacks—that includes legal, and a lot of illegal guns.

The Wall Street Journal reports that illegal firearms, sourced primarily from one-time warzones like the countries that once comprised Yugoslavia, outnumber legal ones in 2017 by 10 million (44.5 million to 34.2 million). Plus, there has been a 10 percent rise in legal gun ownership recently. The reason many new gun owners across the pond give for their firearm purchases is that they are responding to civil unrest and terror attacks, the story says.

Women like Carolin Matthie decided to get a gun permit after hundreds of sexual assaults occurred on New Year’s Eve in several German cities three years ago, the WSJ story says.

“If I don’t do it now, I will have to wait maybe another half year,” the 26-year-old Berlin student told the The Wall Street Journal about her decision to apply, afraid that an uptick in permit applications from other women interested in protecting themselves would cause delays in processing time.

In the time period from 2012 to 2017, the number of legally registered weapons rose to 6.1 million in Germany, about a 10% increase, according to Germany’s National Weapons Registry. The Wall Street Journal reports that permits allowing individuals to posses firearms outside of shooting ranges showed more than a three-fold increase, rising to 9,285 in the same time frame.

In Belgium, France and Germany, most registered guns may only be used at shooting ranges. Permits to bear arms outside of shooting ranges are extremely difficult to obtain, though the number of applications for carry permits is also rising.

Despite the difficulties in obtaining a firearm permit—most European countries require monitored shooting practice and tests on regulations in addition to background checks—The Wall Street Journal notes the increase has been rapid.

The WSJ story points out that the strict regulations have also caused an increase in illegal weapons.

“Europe represents the largest market for arms trade on the dark web, generating revenues that are around five times higher than the U.S.,” concluded a recent Rand Corp. report.

In July 2016, an 18-year-old shooter killed nine people in Munich using a gun authorities concluded he bought illegally off the dark web.

“It’s clear that illegal guns are used mostly by criminals,” Nils Duquet of the Flemish Peace Institute, a Belgian research center, told the The Wall Street Journal, noting that armed robbery and similar crimes are typically conducted with illicit guns.

“Before 2006, you could buy rifles simply by showing your ID,” recalled Sébastien de Thomaz, who owns two shooting ranges in Brussels and previously worked in a gun store. Firearm license applications in Belgium nearly doubled after the terrorist attacks in Paris at the end of 2015 and the one in Brussels at the start of 2016. Now, the lengthy process involves nearly a year of shooting and theory tests, plus psychological checks.

“With each terror attack, the legislation gets stricter,” de Thomaz told the The Wall Street Journal. “For the black market, everything stays the same.”