Historically, nusubito (or common thieves) were regarded as expert in certain elements of ninjutsu (i.e. infiltration, stealing, scamming, etc.). Studying ninjutsu for modern applications then, requires that we learn from the ways of thieves. By studying thieves, we can enhance our awareness of security -its bypasses and strengths- and can better understand the mechanisms of criminal behavior. In the vid. below, armed burglars display a small few of their tactics for invading homes.
Notice how the intruders operate as a unit. Two of the three men take watch positions as the third kicks in the door. Two of the intruders are armed and all of them are wearing clothing that appears normal for the area they are thieving in. One has even gone so far as to wear a large rucksack which might serve to convince someone that he is simply a hiker looking for directions. Once the door is knocked in, one of the men stands watch while the other two burglarize the residence. These home invaders operated as a unit, implying that they are experienced.
The next vid. exhibits a two man team. One stands watch while the other kicks the door in. Goes to show that deadbolts don’t hold up against a well placed kick. What would have happened if someone answered the door? Answer: The invaders would probably have a pre-concocted story for the occupant and come back at a later time. If they are more aggressive, then violence could be expected. For this reason, I answer my door with tools nearby. The samurai of old would position their weapons by the entrances to main living areas for somewhat the same reason. Should an assault occur the weapon he was skilled with would be close at hand. Again, I want to draw particular attention to how easy it is for these criminals to knock a door in. As one of my relatives used to say, “Locks only keep honest people out”. In other words, do not rely on your deadbolt keeping intruders out. Bar the doors and windows, or reinforce them. You can also lay traps within (non-lethal of course) that will make them cautious or think twice about continuing with the burglary. For example, you could use Ashi Garami.
This last vid. consists of interviews with seasoned home-invaders. Well worth a watch.