The European Union’s police agency warned Friday that dozens of Islamic State militant group (ISIS) fighters could already be on European soil, plotting to launch new attacks and possibly evolving their tactics to include suicide car bombings and kidnappings.

In a report about the threat ISIS poses to the 28 EU member states, Europol painted a bleak picture of what the bloc can expect in the near future in terms of the growing extremism threat.

The police agency said that estimates from some intelligent services indicate “several dozen people directed by ISIS may be currently present in Europe with a capability to commit terrorist attacks.”

French troops patrol outside the Eiffel Tower on January 12, 2015 in Paris, France. A Europol report on the threat that ISIS poses to Europe has warned that the group could use suicide bombs on the continent.JEFF J MITCHELL/GETTY

Europol said that the countries fighting in the U.S.-led coalition against ISIS in Iraq and Syria are most vulnerable to attacks and the most likely methods would be those witnessed in attacks committed since the group’s rise in 2014. These include stabbings by individuals, as witnessed in the southern German town of Wuerzberg in July, and the mass shootings and suicide bombings seen in the November 2015 Paris attacks.

As ISIS suffers defeat on the battlefield in Iraq and Syria, Europe faces a new threat as the militant group’s foreign fighters may attempt to return to Europe.

Europol estimates that at least 5,000 EU nationals have traveled to the Middle East to fight for radical Islamist groups, and a third of those have returned.

Speaking to Newsweek in September, Europol chief Rob Wainwright warned that there will be further attacks in Europe, failed or successful.

“Whether or not it is large scale and as devastating as we saw in Paris and Brussels, that is more difficult in terms of speculation,” he said. “but I think we can pretty confident that there will be further attempted attacks on one level or another. We are certainly not out of the woods yet.”

Friday’s report noted a shift in tactics of jihadist groups operating in Europe, from hard, symbolic targets like the military or police to indiscriminate attacks on civilian targets, as seen in attacks in Brussels and Paris, which targeted a rush-hour metro station, an airport, a national football stadium, cafes and a concert hall.

The U.S. State Department warned earlier this month that Americans should exert caution at festive events in Europe because of a “heightened risk of terrorist attacks,” singling out festivals and Christmas markets.

Sherri Papini’s astonishing and emotional story of being found on Thanksgiving morning on the side of the road after authorities say she was kidnapped and tormented for three weeks is one that kidnapping survivor Elizabeth Smart can identify with.

Smart, now 29-years-old, married and an advocate for victims of abuse, was just 14 when she was abducted from her Salt Lake City home and held captive for nine months. Weighing in on Papini’s ordeal, she told ABC News that the California mom will have to create a whole new sense of normal for herself in order to heal.

“It’s really important for people to realize that when a victim comes back, whatever they did, they did to survive,” she said.

Smart explained what kept her going during her own ordeal.

“I found my one thing that I could hold onto no matter what that my captors couldn’t take away or change, was my family,” she said. “And I imagine the same would be true for Sherri. I would imagine that she held onto them. She survived for them.”

Longtime victims' advocate John Walsh, the former host of “America’s Most Wanted” and co-founder of the National Center for Missing and Exploited Children, also weighed in on the case and the road to recovery.

“It’s a desensitizing, mind-breaking experience,” he said. “People have to be patient. Be patient with these victims because they’ve been through hell.”

Smart had some additional advice.

“I would suggest to Sherri to focus on herself, focus on her family, focus on healing,” she said. “You never go back to normal. You have to find a new normal.”

Much more of Sherri Papini's story, including ABC News’ exclusive interview with her husband, will air in a special edition of "20/20" tonight at 10 p.m. ET.

(abcNEWS)