However, the time and resources to carry out such luxurious preparations are not always there. Not every attacker can field an overwhelming force of specially trained and equipped men with reinforcements standing by. Information about the inside of an enemy-held building or vehicle may not be accessible beyond studying it through binoculars or a rifle scope. While some attackers can go to the lengths of wearing the enemy down by siege or even tunnelling under them, others must get the current job done immediately with the force available in order to move on to the next.