If the initial shock failed to breach the defenses, additional fireteams would press on behind them and attack the same point until a breach was created. Once penetration was achieved, the bulk of the Chinese forces would move into the enemy rear and attack from behind. During the attacks, the Chinese assault teams would disperse while masking themselves using the terrain, and this made it difficult for UN defenders to target numerous Chinese troops. Attacks by the successive Chinese fireteams were also carefully timed to minimize casualties. Due to primitive communication systems and tight political controls within the Chinese army, short attacks were often repeated indefinitely until either the defenses were penetrated or the attacker's ammunition supply were exhausted, regardless of the chances of success or the human cost.