Story highlights The CIA director said Monday ISIS members have "gone to school" on new ways to avoid authorities

Earlier, President Obama's national security team suggested the threat remains greater in Europe

Antalya, Turkey (CNN) ISIS probably has plans for more attacks "in the pipeline," according to the head of the CIA, although President Barack Obama's national security team said over the weekend that the threat to Europe is greater than it is to the U.S.

"I certainly would not consider it a one-off event," said CIA Director John Brennan, speaking at a Center for Strategic and International Studies forum in Washington on Monday.

"It is clear to me that ISIL has an external agenda, that they are determined to carry out these types of attacks," he continued, using another term for ISIS. "This is not something that was done in a matter of days. This was carefully planned over the course I think of several months, in terms of making (sure) they had the operatives, the weapons and the explosives with the suicide belts."

He concluded, "And so I would anticipate this is not the only operation that ISIL has in the pipeline."

Photos: Night of terror: Paris attacks Photos: Night of terror: Paris attacks A forensic scientist works near a Paris cafe on Saturday, November 14, following a series of coordinated attacks in Paris the night before that killed scores of people. ISIS has claimed responsibility. Hide Caption 1 of 32 Photos: Night of terror: Paris attacks Police are out in force November 14 near La Belle Equipe, one of the sites of the terror attacks. Hide Caption 2 of 32 Photos: Night of terror: Paris attacks Forensic police search for evidence inside the Comptoir Voltaire cafe after the attacks. Hide Caption 3 of 32 Photos: Night of terror: Paris attacks Shoes and a bloody shirt lie outside the Bataclan concert hall on November 14. Most of the fatalities occurred at the Bataclan in central Paris. Hide Caption 4 of 32 Photos: Night of terror: Paris attacks Security forces evacuate people on Rue Oberkampf near the Bataclan concert hall early on November 14. Hide Caption 5 of 32 Photos: Night of terror: Paris attacks Medics evacuate an injured woman on Boulevard des Filles du Calvaire near the Bataclan early on November 14. Hide Caption 6 of 32 Photos: Night of terror: Paris attacks Police, firefighters and rescue workers secure the area near the Bataclan concert hall on November 14. Hide Caption 7 of 32 Photos: Night of terror: Paris attacks A man with blood on his shirt talks on the phone on November 14. He is next to the Bataclan theater, where gunmen shot concertgoers and held hostages until police raided the building. Hide Caption 8 of 32 Photos: Night of terror: Paris attacks Police officers patrol the area around Notre Dame cathedral in Paris on November 14. Hide Caption 9 of 32 Photos: Night of terror: Paris attacks Police officers patrol Paris' Saint-German neighborhood on November 14. Hide Caption 10 of 32 Photos: Night of terror: Paris attacks Victims of the shooting at the Bataclan concert venue in central Paris are evacuated to receive medical treatment on November 14. Hide Caption 11 of 32 Photos: Night of terror: Paris attacks A woman is evacuated from the Bataclan theater early on November 14. Hide Caption 12 of 32 Photos: Night of terror: Paris attacks Forensics are working in the street of Paris after the terrorist attack on Friday, November 13. The words "horror," "massacre" and "war" peppered the front pages of the country's newspapers, conveying the shell-shocked mood. Hide Caption 13 of 32 Photos: Night of terror: Paris attacks Rescuers evacuate an injured person near the Stade de France, one of several sites of attacks November 13 in Paris. Thousands of fans were watching a soccer match between France and Germany when the attacks occurred. Hide Caption 14 of 32 Photos: Night of terror: Paris attacks A survivor of the terrorist attack in the Bataclan is assisted following terror attacks, November 13. The violence at the Bataclan, which involved a hostage-taking, resulted in the highest number of casualties of all the attacks. Hide Caption 15 of 32 Photos: Night of terror: Paris attacks Spectators invade the pitch of the Stade de France stadium after the international friendly soccer match between France and Germany in Saint-Denis. Hide Caption 16 of 32 Photos: Night of terror: Paris attacks Spectators embrace each other as they stand on the playing field of the Stade de France stadium at the end of a soccer match between France and Germany in Saint-Denis, outside Paris, on November 13. Hide Caption 17 of 32 Photos: Night of terror: Paris attacks A body, covered by a sheet, is seen on the sidewalk outside the Bataclan theater. Hide Caption 18 of 32 Photos: Night of terror: Paris attacks Rescuers evacuate an injured person on Boulevard des Filles du Calvaire, close to the Bataclan concert hall in central Paris. Hide Caption 19 of 32 Photos: Night of terror: Paris attacks Wounded people are evacuated outside the scene of a hostage situation at the Bataclan theater in Paris on November 13. Hide Caption 20 of 32 Photos: Night of terror: Paris attacks A medic tends to a wounded man following the attacks near the Boulevard des Filles du Calvaire. Hide Caption 21 of 32 Photos: Night of terror: Paris attacks A woman walks past police and firefighters in the Oberkampf area of Paris. Hide Caption 22 of 32 Photos: Night of terror: Paris attacks A riot police officer stands by an ambulance near the Bataclan concert hall in central Paris. Hide Caption 23 of 32 Photos: Night of terror: Paris attacks Wounded people are evacuated outside the Bataclan concert hall. Hide Caption 24 of 32 Photos: Night of terror: Paris attacks Police secure the Stade de France in Saint-Denis, north of Paris, following explosions during the soccer match between France and Germany. Hide Caption 25 of 32 Photos: Night of terror: Paris attacks A wounded man is evacuated from the Stade de France in Saint-Denis, outside Paris. Hide Caption 26 of 32 Photos: Night of terror: Paris attacks Spectators gather on the field of the Stade de France after the attacks. Explosions were heard during the soccer match between France and Germany. Hide Caption 27 of 32 Photos: Night of terror: Paris attacks French security forces rush in as people are evacuated in the area of Rue Bichat in the 10th District of Paris. Hide Caption 28 of 32 Photos: Night of terror: Paris attacks People leave the Stade de France after explosions were heard near the stadium during a soccer match between France and Germany on Friday. Paris Deputy Mayor Patrick Klugman told CNN President Francois Hollande was at the match and was evacuated at halftime. Hide Caption 29 of 32 Photos: Night of terror: Paris attacks Victims lay on the pavement outside a Paris restaurant. Hide Caption 30 of 32 Photos: Night of terror: Paris attacks Rescue workers and medics tend to victims at the scene of one of the shootings, a restaurant in the 10th District. Attackers reportedly used AK-47 automatic weapons in separate attacks across Paris, and there were explosions at the Stade de France. Hide Caption 31 of 32 Photos: Night of terror: Paris attacks French security forces move people in the area of Rue Bichat in the 10th District. A witness told BFMTV that firefighters were on the scene to treat the injured. Hide Caption 32 of 32