David Kilcullen wrote an article for the National Interest about the war against ISIS:
By late 2013, when ISIS fighters mounted a major push against the Iraqi cities of Tikrit and Fallujah, their tactical style had settled into a pattern. A main force, often comprising dozens of trucks and troop-carrying technicals, would move in compact formation on highways and secondary roads. Ahead of it, and to the flanks, a swarm of gun trucks—technicals with anti-armor weapons, heavy machine guns, radios and a few dismounts—ranged widely across the landscape, scouting routes, securing chokepoints, and looking for targets of opportunity or soft spots. When they spotted one, they would either “bounce” and overwhelm it with their own resources, or pull the main column onto it using radio and cellphone messages. Teams of two to three technicals, each carrying six or eight fighters ready to dismount, would swarm onto a target, coordinating their fire to overwhelm it. This is classic maneuver warfare—in the business, it’s known as “recon pull”—and it looked a lot like Soviet-style mission tactics, which was unsurprising given the number of Ba’athist officers now on the ISIS payroll.
But there were a couple of variations. First, ISIS columns at this time (we’re talking early 2014 now) operated in much tighter formations than a western armored force would do, clumping together in relatively large columns. They had little to fear from Iraqi air power or artillery: instead of dispersing to protect against these kinds of threats, their formations were optimized for mutual support against a ground-based enemy. Second, unlike conventional troops (or, even, many guerrilla organizations) they made extensive use of suicide bombers, often in improvised armored vehicles, as primitive guided weapons—leading assaults, clearing roadblocks and obstacles, and creating shock effects that could be exploited by the main column to bypass strongpoints or seize defended locations.