In the wake of the deadly attacks in Paris this month, authorities are conducting raids in Europe, raising fears among citizens that the terrorism that has occurred around the world during the past year -- ranging from hostage crises to mass murders -- could be imminent in their hometowns. But experts say that even though there has been an increasing number of high-profile terrorist attacks carried out by Islamist jihadists in recent months, most if not all of them were disconnected, and were inspired by what is becoming the new norm in the terrorism world: waging jihad as part of a widespread, but disjointed, social movement.

“People are trying to make order out of chaos,” said Clint Watts, a former U.S. counterterrorism official. “But there is still a lot we don’t know. A lot of these guys were acting on their own.” Watts said there are three kinds of terrorists in operation, inspired, networked and directed terrorists. He said the networked and inspired terrorists have carried out the majority of the most recent attacks and did not have personal connections to the leaders of the main terrorist organizations. Their lack of connection to the leaders of groups like al Qaeda make them difficult to track, he said.

French officials vowed after the attacks that killed 17 people and wounded dozens that they would find ways to ramp up security measures to prevent another massacre. But domestic measures may not be enough to stop another attack from happening, experts say, because the terrorism environment is much more widespread and dispersed than ever before. Currently there is no fully functional international system that systematically tracks foreign fighters -- the people authorities have described as the most dangerous.

Information released by French officials after the attacks this month revealed that the Kouachi brothers, the two men who killed staff members of the weekly satirical magazine Charlie Hebdo on Jan. 7, had ties to al Qaeda and had traveled to Yemen via Oman in 2011. 

“These two brothers arrived in Oman on July 25, 2011, and from Oman they were smuggled into Yemen, where they stayed for two weeks,” a senior Yemeni security official told Al Jazeera. “They met [al Qaeda preacher] Anwar al-Awlaki and then they were trained for three days in the deserts of Marib on how to fire a gun. They returned to Oman and they left Oman on Aug. 15, 2011, to go back to France.”

French officials said they had known about the Kouachi brothers before the attack on the Charlie Hebdo office and released one of them from jail after he was arrested for ties to terrorism. Despite French officials knowing about the attackers, they were unable to prevent the Charlie Hebdo massacre.

It is still unclear how many foreign officials knew of the Kouachi brothers and were actively keeping tabs on them. The U.S. claimed it had long viewed the Kouachi brothers as potential terror suspects and even placed them on the so-called no-fly list, as reported by Yahoo News. And officials in Yemen had known of their presence in the country.

Despite some information sharing about the Kouachi brothers, the two were still able to carry out the attack that killed 12 people, which raises questions about the capability of foreign fighters to carry out more terrorist plots in the West.

At a joint press conference Friday, U.K. Prime Minister David Cameron and U.S. President Barack Obama addressed the terrorist threats to both of their nations.

“In the last six years since you became president, and in the nearly five years I have been prime minister, we have faced some big issues on our watch,” Cameron said. “Those challenges have boiled down to one word: security.”

Both leaders said they needed to work on new measures to track individuals linked to terrorist cells. 

“Since we can’t control kids going into a school shooting, we sure can’t stop terrorists everywhere,” said Mia Bloom, a professor at the Center for Terrorism and Security Studies at the University of Massachusetts Lowell. She added that one of the reasons Islamist terrorists are hard to track is their lack of command structure.

“Most of these attackers didn’t know they were al Qaeda until we told them they were,” the former U.S. counterterrorism official Watts said. “Most of the individuals who carried out recent attacks were not directed by leaders in al Qaeda or the Islamic State group. Most of them plan on their own, carry out the attack, and then ask for recognition.”

According to a report published by the New York-based Soufan Group and the London-based International Center for the Study of Radicalization, the total number of foreign fighters in Syria in September was between 11,000 and 12,000. 

In September, Interpol announced the formation of a dedicated Interpol Foreign Terrorist Fighter, or FTF, program in partnership with the U.S. National Security Council, Department of Justice and Department of Homeland Security. The program was designed to “monitor and deter [foreign terrorist fighters’] international movement and interdict them at strategic entry points, where possible,” the Justice Department said in a statement. But it is unclear whether this program has been implemented.

The Justice Department said in September that Interpol was “taking the lead on implementing it in the United States,” but provided no timeline of when that process would be completed.

The program has a working group including Australia, Belgium, Canada, France, New Zealand, Spain, Switzerland, the Netherlands, Turkey, the U.K. and the U.S., which all provide information to a database with criminal intelligence.

Before the formation of the FTF program, Interpol employed its so-called Red Notices to target and apprehend terrorists for prosecution in U.S. courts and its so-called Blue Notices to trace and locate terrorists and others suspected of terrorism-related activity. But the notice system relied on individual countries to take the initiative and check the notices published by Interpol, and provided no systematic way for governments to share information.

The FTF program is going to establish an “analytical database populated with information contributed by participating member countries,” the Justice Department wrote in a note to International Business Times. “Law enforcement and border authorities can leverage this valuable information when making determinations of terrorist threats posed by subjects located in, or attempting to enter, their respective jurisdictions.”

Outside the FTF program, individual terrorism research organizations are conducting their own studies of the movement of foreign fighters. Watts said he constantly updates his own database that tracks foreign fighters through social media and other forms of communication.

Watts said that instead of tracking fighters flocking to places such as Iraq and Syria, authorities should be focusing on those who are staying behind. 

“ISIS is losing ground in Syria, which means they are resorting to more conventional methods at home in Europe,” Watts said. “It’s like a yo-yo: What goes down on one side goes up on the other.”