Last week, a crude bomb exploded in the London Tube, injuring 30 people. The attack, for which the Islamic State has since taken responsibility, marked the fifth act of terror in England this year and is indicative of broader, systemic issues embedded in British culture as well as changing global trends, say two experts in European politics and Middle East Policy.

Part of the issue is a rise in terror attacks around the world, said Mai’a Cross, Northeastern’s Edward W. Brooke Professor of Political Science, whose research focuses on European politics and foreign and security policy.

“This isn’t something that’s isolated to the U.K.,” she said. “We’ve seen numerous terrorist attacks across Europe, and it’s indicative of broader trends globally. We’ve seen this uptick in radicalization, particularly with the help of social media; more radical ideas are spreading throughout the world.”

Homegrown terrorism

Another issue is the growing threat of homegrown terrorism.

“There are certain communities in the United Kingdom—certain pockets—that end up being breeding grounds for extremism,” said Hassan Hassan, resident fellow at the Tahrir Institute for Middle East Policy. “Some of the best-known jihadi ideologues have lived in London at some point in their lives.”

Part of the draw, Hassan noted, is the judicial system in place in the U.K., which is slower to crack down on “clerics and activists” who spread extremist views.

Unlike the U.S., which issued far-reaching information-gathering measures after 9/11—in the form of the Patriot Act—the U.K. is more hesitant to infringe on citizens’ personal privacy in the name of counterterrorism, Cross said.

“The key difference that’s evolved in the past decade or so between U.S. and European Union counterterrorism is that the European governments have more restrictions on what can and can’t be gathered because they want to maintain the security of their citizens’ privacy,” she said. “They have very clear rules established by their parliaments to protect citizens’ right to privacy, and this has some effect on what they can do when they intend to pursue terrorist links.”

Hassan posited that the difference in attitudes was likely due to the fact that the U.K. simply hasn’t experienced a terrorist attack as devastating as 9/11. Cross pointed to something deeper. “I just think there’s a more fundamental difference,” she said. “European countries have a long history of having more social democratic states. The two regions are just on different footing.”

The role of geography

Other fundamental differences in Europe’s geographic structure have also made it a prime target for terrorism, Cross said. “More foreign fighters and Europeans are traveling to Syria through Turkey, becoming radicalized, then returning home,” she said. “Thousands of fighters have gone and come back. That’s something specific that’s reliant on the location of Europe in some respects—because of the freedom of movement within Europe, it makes it easier to plan things in one place and carry them out in a totally different city. We’ve seen Brussels become a hotbed for some of this planning.”

Indeed, several deadly terror attacks have been carried out in Europe in the past two years alone. For example, in July 2016, a truck deliberately plowed into a large crowd in Nice, France. In March 2016, three blasts shook Brussels: two at Zaventem airport and one in a subway station. In November 2015, there was a coordinated string of attacks at several venues across Paris.

“This is not all about people coming from the outside into Europe,” Cross said. “A lot of this is homegrown radicalization as well.”

Brexit complications

An additional layer to all this is Brexit. Since negotiations are ongoing, it’s unclear what the exact terms will be for the U.K. leaving the EU. The degree to which it does could have major impacts on Great Britain’s ability to collect and ascertain counterterrorism intelligence.

“Instead of a system where all Europeans collectively help collect this sort of information, the U.K. would be entirely on their own,” Cross said. “They’re suddenly on their own, and likely to find themselves outside this zone of information that the EU represents. That makes it far less effective to track criminals who commit crimes in one country and travel to another.”