Interior Minister Hans-Peter Friedrich told The Associated Press that terrorist activities by Muslim extremist organizations have evolved to be decentralized, making their activities harder to track for authorities.
"What worries us" is that there will likely also be more lone wolf attackers who are not directly connected to a major terror group but have radicalized themselves, often through propaganda available online, he said. "There will likely be more of them because the Islamists' propaganda networks seem to be further gearing up."
"There is no more centralized planing... Single terror cells are being sent out, complete with information and propaganda. This is what worries us," he said.
Friedrich is headed to Washington next week to meet with officials such as President Barack Obama's top counterterrorism adviser John Brennan and Attorney General Eric Holder to discuss terrorism and cyber security issues.
There have been several unsuccessful or foiled attacks by Islamic radicals in Germany, and the first fatalities attributed to a Muslim extremist came last year in March when a 21-year-old Kosovo-born ethnic Albanian gunned down two U.S. airmen outside Frankfurt's airport. The lone attacker is believed to have been inspired by watching Salafist videos online.
Salafist groups—espousing an ultraconservative interpretation of Islam—have recently increased their presence and followers in Germany.
One radical group attracted as much public attention as criticism from officials this month after announcing it plans to distribute millions of free copies of the Muslim Holy Book, the Quran, in Germany.
"In this context it is worrying us that they are strengthening their propaganda and that they are explicitly targeting to win over young people," Friedrich said.
He also said cyber crime also is concerning security officials since hacking and spy attacks could target companies and the country as a whole, including its critical infrastructure.
Stuxnet—a sophisticated virus that targeted Iranian nuclear installations—"came as a warning to all of us that much more is already possible to be done with malware and virus programs than one had imagined," Friedrich said.