Yes, I believe that the terrorists have expanded their reach because of the war going on in Syria. Syrian refugees are forced to flee to Europe because of the constant bloodshed in their country, and terrorists are posing as refugees in order to enter Europe. Germany is one of the countries that has accepted the most Syrian immigrants, and I believe it is possible that some terrorists now are living in Germany.
Drug scene and mafia taking control in leftist crime-tolerant Berlin, this was just a matter of time to happen. Surely the police wouldn't cover up an act of terrorism in case it was blamed on migrants? Or would they? Once governments and their agencies are found to have been covering things up, it is very difficult to trust them again.
I can't agree with this question, because there isn't enough evidence to support that in fact, it was, or was not terrorists. There is a possibility of it being a random act, of a specific person against another specific person. If it is terrorism, then Germany needs to join in the fight against it.
Saying the terrorists have expanded is a difficult argument to make, because the past several years have shown that terrorism is a global threat. Look at 9/11, the Madrid train bombings, attacks in Mumbai, and recently the attacks in France. Also look at smaller-scale attacks, personnel-wise, like attacks on military bases and the Boston Marathon bombings.