Security measures are being stepped up in Germany after Interior Minister Thomas de Maiziere said there were clear indications of a terror plot targeting the country. BBC Berlin correspondent Stephen Evans looks at Germany's evolving position on the risk of attacks.
The minister has not given the specifics of whatever plot his security services think they now have information about, but he did bring different strands together.
Firstly, he said information had come from another country: "Since the middle of 2010, the security services have noticed increased indications that the terrorist organisation al-Qaeda has been planning attacks in the United States, in Europe and in Germany."
He said officials now had more details which justified increased concern about "sustained efforts" to mount an attack, both within Germany and outside: "It is the unanimous assessment of the security services that we are currently dealing with a new situation."
He also indicated that the information emerged from the attempt to bomb two aircraft on their way to Chicago last month - both with printer cartridges loaded with explosive. One of the aircraft went through Cologne airport with the bombs undetected.
That German link may or may not be pure coincidence.
It does, though, seem that there were warnings of those attempted attacks from intelligence sources in the Middle East.
So the new warning raises the question of whether those original sources of information for the bombs destined for the US now have new information about a new plot involving Germany.
On top of that, last year, about 12 militants who attended a mosque in Hamburg - the same mosque attended by the 9/11 leader, Mohammad Atta - went missing.
Western security services reckon they then resurfaced in training camps in Afghanistan and northern Pakistan. At least one of them was killed in an attack by a United States pilotless drone attack.
But another was captured and appears to have been giving information to the American authorities in Afghanistan. It is hard to see how he could be the source of the new information, because he has been in custody for some months now.
The question is - what has become of the rest of the Hamburg cell?
When a month ago the US and Britain said their security services had information about plans to attack targets in Paris, Berlin and London, Mr de Maiziere was dismissive.
When he gave his news conference in Berlin on Wednesday, his demeanour was much changed. It exuded seriousness. He said there was reason for "concern but not for hysteria".
Germany may be a target because its troops are in Afghanistan, though not in a frontline role - its post-World War II constitution forbids that.
But it also seems likely target because of its central position in Europe. After the 2008 Mumbai attack, in which gunmen killed 166 people in various sites, including a hotel, the fear is clearly of a repetition in a prominent European city like Berlin.
Despite Germany's position as a country with hardline militants, it has not experienced any of the bloodshed suffered by New York or London - though in 2006, two Lebanese men tried but failed to detonate bombs on two trains in Cologne.
The triggers on canisters of propane gas went off but failed to detonate an explosion.
German security services now seem to have hard information about another determined attempt to kill.
The interior minister did not indicate how detailed the information on the plotters was - or how far from being caught they might be.