– British Prime Minister David Cameron said the international community must show resolve in combating the “death cult” of Islamist extremism, as security across Europe was increased after the recent attacks in France.

European ministers will meet in Brussels on Monday and in London Thursday to discuss their response to the terrorist threat.

“What these terrorists represent is the perversion of a major religion,” Cameron said on the CBS program “Face the Nation” during a visit to Washington. “They’re not its true adherents, they are fanatics who’ve attached themselves to a death cult. What we’re engaged in is a very long struggle where we’ll have to show real perseverance.”

Monday’s meeting of European Union foreign ministers is expected to be dominated by the struggle to fight terrorism across the continent after the attacks earlier in January in France, in which 17 people were killed by Islamist extremists. The meeting in London, involving more than 20 countries including the United States and Arab states, will focus on defeating the Islamic State in Iraq and the Levant (ISIL), the radical group which dominates large areas of Syria and Iraq.

European terrorists have been inspired by ISIL and there is increasing concern about the influence returning fighters are having on domestic extremists. Belgian prosecutors said some members of a terrorist cell broken up last week, when two people were killed by officers, had returned from fighting in Syria.

“This threat keeps morphing, because it’s the same fundamental problem: extremist Islamist terror,” Cameron said. “But whereas the majority of it was coming from the Afghanistan-Pakistan area, now you see more of it coming out of Iraq and Syria. What I don’t want to do is try and posit that there’s some clash of civilizations going on, because that is what the terrorists want.”

A group of about 30 British women based in northern Syria have been using social media accounts to recruit extremists to carry out attacks in Britain, the Observer newspaper reported, citing research by the London-based International Center for the Study of Radicalization.

Security forces have arrested at least 28 people across the continent since the Paris attacks and the threat is an “urgent and very serious challenge,” Europol Director Rob Wainwright told Sky News Saturday.

As many as 300 soldiers are being deployed in Belgium to protect potential targets such as Jewish neighborhoods and embassies.