From my newspaper, Frankfurter Allgemeine:
The spying attempts at Stuttgart airport could have a terrorist background. According to the German Press Agency, at least one of the suspects belongs to the Islamist milieu. Previously it had been said that he was classified as a danger. According to the dpa sources, this could not be confirmed beyond doubt at first. It was also said that four suspects were currently being targeted. Security circles confirmed corresponding information to the German Press Agency on Thursday. Previously, Südwestrundfunk (SWR) had reported on this. Two of the wanted were father and son from North Rhine-Westphalia. They had already attracted the attention of the French police last week when they took photos of the terminal at Paris' Charles de Gaulle airport. According to the SWR report, these were also the two men sighted at Stuttgart Airport. According to the report, they could be identified on the basis of video recordings. The responsible police headquarters in Reutlingen did not want to comment on the report. The investigation is being conducted by the public prosecutor's office in Stuttgart, which, however, did not comment on Thursday evening upon request.
According to a report in the newspaper "Tagesspiegel" referring to security circles, young men were filmed by a surveillance camera last week and on Wednesday. The persons had stayed at the security gate without wanting to take a flight and without luggage. Against this background, the Federal Police had deployed the so-called Special Unit SFOE plus at the airport to prevent an attack.
According to a ZDF report, two people in Paris-Charles de Gaulle took photos in the terminal area of the airport in the evening of 13 December. They then drove away in a van with a German license plate. After evaluating the surveillance videos, French terror investigators contacted their German colleagues; they found a trace to the Islamist. In addition, two people are said to have spied on Stuttgart airport last week. There is evidence of a direct connection. According to ZDF television, it was preliminary investigations for possible terrorist attacks.