In #1, the assailant (on right) is standing with his left side to the camera, and his right hand, though empty for the purpose of the illustration, could easily be holding a weapon with which to strike at the defender, whose responses may well be the same whether the hand is empty or not. Two methods of defense will illustrate this point.
The defender has already, in #1, intercepted the assailant's right arm with a sweeping open-handed catch of that arm from the inside, using his left hand to grasp the attacking arm between the elbow and the wrist. Following Method A, the defender pulls the assailant's attacking arm forward and downward, thus jerking him off-balance and forwards. The defender simultaneously strikes with his opened right hand, using a knife-edged formation, at the assailant's head (#2). The assailant's reaction to this blow is one of shock as he, at the same time, attempts to resist the forward movement imposed on him by the defender. This he does by straightening his body and leaning backward, putting himself off balance backwards. Even had the defender's intended blow fallen short, the combined action would have had the all important effect of moving the assailant back. The defender utilizes this reaction of the assailant to throw him backwards to the ground. He does so by putting his right leg behind the assailant's right leg and, using the combined power of both his arms, forces the assailant further backward over the outstretched leg (#3).
Note that the defender does not step forward until he has obtained a rearward movement from his enemy. This is a safeguard: if the assailant does not react by moving backward, the defender is still in a position to deliver a forward snap-kick into the groin of his enemy.