instructions that isis has put out in its social media channels before with instructions to their followers on how to carry out such an attack. >> reporter: one of the most popular instruction manuals saipov might have read online? this one in the isis magazine last year. it discusses how to use rental trucks to attack crowds and inflict maximum casualties. . quote, vehicles are like knives, it said, and urges attackers to alliance of their terror group and an example of such would be writing on dozens of sheets of paper the islamic state will remain. very similar to a note officials say saipov left in his vehicle. >> the gist of the note was that the islamic state would endure forever. >> reporter: for isis, experts say lone wolves offer an easier way to strike at soft targets without the planning and skill used in attacks like paris. >> it doesn't have multiple pieces. you're not dealing with multiple cells or people that you have to coordinate with. you have to make sure that your