Just a week into the year, France has already been rattled by an attempted attack on a police station, but counter-terrorism officials have far graver fears for Europe in 2016.

November's attacks in Paris, in which 130 people were killed by Islamic State group jihadists, showed the trauma that could be caused by a group of men with Kalashnikov rifles, but experts fear it could be just the start.

Source: b'Representational image | Source: Reuters'

"Unfortunately, I think 2015 was nothing," a counter-terrorism official said on condition of anonymity.

"We are moving towards a European 9/11: simultaneous attacks on the same day in several countries, several places. A very coordinated thing. We know the terrorists are working on this," he added.

He said the Islamic State group was recruiting and training Europeans "with the goal of sending them back to hit their countries of origin".

"They have the necessary false documents, the mastery of the language, the sites, the weapons. We stop a lot of them, but it must be recognised that we are overwhelmed. Some will get through — some already have."

Source: b'Security in Paris | Source: Reuters'

Recent arrests of jihadists returning from Syria and Iraq have added to concerns, he said.

"The profiles are changing. We are seeing ultra-radical guys return, very battle-hardened, who should have stayed over there.

"Before we mostly had guys returning who had made a mistake, who didn't realise that war can be painful. But now, we are seeing guys return who are sticking to their chosen path."

Faced with an enemy that is happy to die and maximise civilian casualties, the challenge for France's security forces is to massively speed up response times.

"There will always be a delay for intervention forces that we have to reduce as much as possible," colonel Hubert Bonneau, head of the elite GIGN police, said.

Source: b'Police cordon off area near blast site during Paris attacks in 2015 | Source: Reuters'

"In the Bataclan, the killing of 90 people took 20 minutes. It stops when there is the opposition of security forces," he said, referring to the attack on a Paris concert hall on November 13.

It took two-and-a-half hours for police to storm the concert hall as they tried to gather information on the layout of the building and position of the jihadists.

Bonneau said this new type of threat meant there were no classic hostage situations such as in the past.

"Hostages are just a buffer to slow the progress of security forces. If we don't intervene as quickly as possible there will be more victims. That's the lesson to draw from the attacks of November 13, that will change our mode of intervention.

"We need to have surgical action, as forceful as possible and as quickly as possible," he said.