Isis' war on Europe seems to have entered a dangerous new phase, evolving from highly coordinated operations on the grand boulevards of Paris and Brussels to amateur assaults in the hinterlands that have suddenly turned anyone, anywhere into a target.
The rapid-fire nature of the attacks in Europe over the past two weeks is confounding European intelligence agencies, at times turning terrorism response into a ground war fought by already stretched local police. Following the latest attack - the brutal slaying on Tuesday of a small-town priest in France - the violence has felt almost like the start of the uprising that Isis (Islamic State) has been attempting to spark among its sympathisers in the West for years.
The attackers have included mentally disturbed individuals inspired by the extremist group - which has in recent months increased its calls for "lone wolves" to act. But other assailants may have maintained at least indirect contact with the group. Adding to the chaos, there have been two additional highly violent attacks in Europe by assailants with no definable political motive at all, including an Iranian German teen who went on a shooting rampage in Munich.
The assailants' weapons: a truck, an axe, a knife and a bomb.Even the four attacks in two weeks claimed by Isis - two in Germany, and two in France including the slaying of the priest - have been terrifyingly different.
Their victims: revellers enjoying Bastille Day fireworks, commuters on a Bavarian train, bystanders at a music festival and the priest. The locations: from small towns to the major coastal city of Nice.
The randomness of the attacks, experts say, is making it even more difficult for security services to do their jobs because the potential targets are virtually limitless, as are the means and the profiles of perpetrators.
"It's a mass diffusion of the phenomenon, and it's quite worrying that we're seeing the attacks go in that direction," said Raffaello Pantucci, a terrorism expert at London's Royal United Services Institute.
"If it's happening in remote villages in God knows where, what does that say for the levels of policing you're going to need across the country?" Pantucci added. "Security forces have already been at full tempo for a very long time. You can't maintain that intensity for a prolonged period."
If there is any pattern, it may lie in what Rita Katz, director of the US-based SITE Intelligence Group, described as an intensification of Isis' long-standing effort to prompt violent acts by its sympathisers living in the West. She said her group, which monitors jihadist activity on social media, has detected an increase in Isis' output since May, when its spokesman, Abu Muhammad al-Adnani, issued an audio recording urging individuals not in direct contact with the group to take action.
"Calls for lone wolf attacks from Isis have increased in the West dramatically, especially after [each new attack] in the West," she said.
The extremist group is also becoming more opportunistic and seeking out new niches. She noted, for instance, that the number of social-media and Isis messages in Portuguese have surged in the two months ahead of the Olympic Games in Rio de Janeiro, which start on August 5. Brazilian officials in recent days arrested 12 suspects - believed to be Isis sympathisers - for allegedly plotting an unspecified attack on the Games.
A US counterterrorism official said some of the recent attacks appear to involve affiliates of Isis, also known as Isil, while others don't.
"We have come to view the threat of Isil as a spectrum where on one end, individuals are inspired by Isil's narrative and propaganda, and on the other end, Isil members are giving operatives direct guidance," said the official, speaking on the condition of anonymity to discuss intelligence matters.
The new pattern is spreading fear in Europe, particularly in enclaves far from capitals like Paris and Berlin that once seemed the most likely targets. For nations already on maximum high alert, it is also severely testing security services, and putting more and more pressure on police.
Police in Germany insist they are at their breaking point.
"There can't be any illusion when it comes to our capacities, especially when several cities are hit at the same time," said Rainer Wendt, federal chairman of the German Police Union. "We need at least 20,000 additional police officers, but even that won't do." The problem, he said, is that the recent attackers were not part of sophisticated terrorist cells. "If Isis did have structures in Germany, we would be able to monitor them," he said.
There are other challenges in countries such as France, where police forces were reduced several years ago because of spending cuts and a desire to streamline a complex array of law enforcement agencies. Also, security services are largely focused on Paris - where the majority of the roughly 10,000 soldiers deployed in the country's counterterrorism operation are based.
Pantucci said it was too soon to know whether the surge of attacks is part of a larger plan by Isis or other extremist groups. Even if it's not, he said, that too could be worrying: Recent attacks may be the work of copycat killers.
"These are people who feel like doing something, they look around at what's happening and decide now's the moment to do it," he said. "They realise: 'I don't have to be in an extremist community. I can just do something and decide that I'm part of a broader cause'." And that, he said, "starts to cause major problems for the security agencies", because for every extremist who opts to attack, there are many others "who have said the exact same things but don't act on the same impulse. You can't stop every psychotic".
Pair pledge allegiance
Two jihadists who attacked a French church and killed a priest pledged allegiance to Isis (Islamic State), a video showed yesterday, as investigators worked to identify the second assailant.
Two men stormed into a church in the northern town of Saint-Etienne-du-Rouvray during mass on Tuesday and slit the throat of Father Jacques Hamel, 86, at the altar before being gunned down by police. Another man was seriously injured, while three nuns and a worshipper escaped unharmed.
One of the attackers was identified as French jihadist Adel Kermiche, 19, who was awaiting trial on terror charges and had been fitted with an electronic tag despite calls from the prosecutor for him not to be released.
Sources close to the investigation said they found an identity card belonging to one Abdel Malik P, also 19, at Kermiche's home, who they believe is the second attacker.
In a video on the Isis news agency Amaq, two men calling themselves by the noms de guerre Abu Omar and Abu Jalil al-Hanafi swear "obedience" to Isis leader Abu Bakr al-Baghdadi.