For decades, European countries have historically maintained some of the heaviest restrictions on civilian gun ownership, leaving the rate of firearms in circulation far below comparable levels in the US and South America. But following a string of high-profile terror attacks in recent years, the number of people applying for legal gun ownership in countries including Germany and Belgium has surged, as European citizens become increasingly concerned about personal security in the face of a wave of Islamic terror and an unchecked migration crisis that has led to a surge in crime.

As the Wall Street Journal reported, in Germany, the number of legally registered weapons rose roughly 10% to 6.1 million during the five years through 2017, the most recent year for which data from Germany’s National Weapons Registry was available. Furthermore, permits to carry arms outside of shooting ranges more than tripled to 9,285 during the same period.

Meanwhile, applications for shooting licenses in Belgium almost doubled following the massacre at a Paris concert venue in November 2015, which was followed four months later by an attack in Brussels, offering "a clear indication of why people acquired them,” according to Nils Duquet of the Flemish Peace Institute, who spoke with WSJ for its story.

Since 2016, there have been more than 16 terror attacks in Europe attributed to ISIS, according to ESRI's terror-attack tracker.

(Courtesy of ESRI)

In Germany, where restrictions on gun ownership are notoriously strict, permits for non-lethal air-powered guns have seen an even larger surge. The number of applications for the weapons, which shoot tear gas or loud blanks, gas roughly doubled in the three years through the end of 2017, to 557,560, according to German government data.

Still, the number of illegal weapons in Europe far outnumbers legal weapons (Western European countries are among the biggest markets for weapons traffickers).

"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 2017, the estimate stood at 44.5 million to 34.2 million, with the weapons typically sourced from the former Yugoslavia or other one-time war zones. Some are even bought online from vendors in the US.

Security has been the primary reason cited by many applicants for gun-carry licenses in places like Germany. According to one woman who was quoted by WSJ, the New Years Eve assault of hundreds of women in the German city of Cologne by a gang of migrants three years ago inspired Carolin Matthie to purchase her first weapon.

When hundreds of women were sexually assaulted on New Year’s Eve in several German cities three years ago, Carolin Matthie decided it was time to defend herself. The 26-year-old Berlin student quickly applied for a gun permit, fearing many women would have the same idea and flood the application process. "If I don’t do it now, I will have to wait maybe another half year," she recalls thinking.

Matthie now vlogs about the importance of using firearms for self defense.

Ms. Matthie first bought an air gun, which her permit allowed her to carry with her. She has since become a sports shooter, using live ammunition at shooting ranges, and is now applying for a firearm permit. She posts a daily video blog where she advocates armed self-defense.

Since 2006, Belgium has been tightening restrictions on gun ownership following a terror attack perpetrated by a teenager with a legally acquired rifle...

"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. "They used to let me shoot with all my stepfather’s guns whenever I joined him at the range," said Lionel Pennings, a Belgian artist who joins his stepfather at one of Mr. De Thomaz’s shooting ranges on Sundays. Mr. Pennings recalled that in the past he could easily fire a few rounds with his stepfather’s gun. "Now it’s much stricter," he said. "You can only use the guns you have a permit for." A Belgian would-be gun owner must pass almost a year of shooting and theory tests, plus psychological checks, said Mr. De Thomaz. The gun-range owner questions the impact of that policy. "With each terror attack, the legislation gets stricter," he said. "For the black market, everything stays the same."

...But following a wave of attacks in Europe, membership in Belgian shooting clubs is soaring. While ownership rates still lag the US and Latin America, as the threat of terror persists and European leaders stand by their pro-migration policies, some day, legal gun ownership in Western Europe could continue to climb.