With the world already on edge following the deadly Paris terror attacks as well as attacks in Mali over the weekend, Islamic State amped up its threats to carry out terror attacks on American soil. But one counter-terrorism expert in Israel said that he is most worried by individual attackers rather than threats from large terror groups.Dr. Ely Karmon, a senior researcher for the International Institute for Counter-Terrorism at the IDC Herzliya said that "for the moment, the most dangerous individuals are those who seem to be 'lone wolves' or [part of] small cells" of people who already live in the US and can more easily slip past the watch of intelligence authorities.The threat to the United States from organized terror groups is still very real, he told The Jerusalem Post on Monday, using the 2011 Fort Hood shooting attack, the attempted Times Square car bomb and the 2013 Boston Marathon attack as examples. But Karmon noted that US authorities have successfully thwarted many more terror attempts, as seen by the fact that since 9/11, there have not been any similar large-scale attacks on American soil.Individuals who show a slant toward terror should be monitored, he said, adding that the FBI already uses undercover sting operations to weed out any suspicious individuals. Still, fears are high after 130 people were killed in Paris on November 13 in a string of terror attacks. In the past few weeks, Islamic State has released two threatening videos. One of the videos interposed images of New York City with a terrorist preparing a suicide bomb vest, released only a week before the city will host its famous Thanksgiving Parade.Karmon lambasted these threatening videos and the way Islamic State tries to scare the public using social media sites, calling it "purely propaganda." "They're trying to influence the morale and psychological behavior of the population," through the use of Youtube videos and Twitter, he said.Later on Monday, the US State Department issued a worldwide travel alert to American citizens ahead of Thanksgiving, one of the busiest travel seasons of the year, and advised people to avoid crowded places."Authorities believe the likelihood of terror attacks will continue as members of ISIL/Da’esh return from Syria and Iraq," the alert reads. "Exercise particular caution during the holiday season and at holiday festivals or events." Karmon felt assured that American security forces were taking the appropriate precautions to keep holiday events safe, noting that they are already aware of the heightened risk posed during holidays. New York will deploy thousands of police officers at the parade, bolstered by a new counter-terrorism unit and an additional unit specifically focused on large protests and other incidents requiring more manpower.