Grunnen til at Tysklands innenriksminister rykket ut og advarte mot en overhengende terrorfare, var et tips fra en terrorist på den afghansk-pakistanske grense om at terrorister planla å angripe Riksdagen. To terrorister skal allerede være på plass i landet.

Det var de konkrete opplysningene som gjorde at politiet og myndighetene trodde på advarslene.

But the caller, who claimed to have been a jihadist working with terrorists in the Pakistan-Afghanistan region, phoned the federal police three times providing what law enforcement officials said was concrete information: plans for a team of armed terrorists to rampage through the Reichstag, the popular tourist site that also serves as the home for Germany’s Parliament.

Even more alarming, the man said that there were already two members of the group in or near Berlin, and that four others would soon be trying to join them, according to the official, who spoke on the condition of anonymity because of his work in intelligence and security matters.

The existence of the caller, who was not identified, was first reported in the German magazine Der Spiegel.

At the moment, the official said, security agencies were focused on four or five possible terrorist plots aimed at different locations around the country. The official said the authorities were uncertain if the plots were linked in one grand scheme or if they were completely separate.

Shortly after the government raised its terrorism alert and closed the Reichstag to tourists, the chancellor, Angela Merkel, called for calm and then in her weekly video podcast, said this was a concern not just for German law enforcement, but for all of NATO: “terrorism, failed states — these are the future challenges against which we have to prepare ourselves.”