In 1930 Ushieba Morihei published “Budo”. In it he clearly shows Atemi striking as a component of his techniques.
Ueshiba Morihei, have made it very clear that atemi was an integral part of his practice.
'Aikido is 99% atemi'. (Ueshiba Morihei as quoted in Traditional Aikido Vol 5 (1974) by Saito Morihiro, p. 38) 'In a real battle, atemi is 70 % technique is 30%'
Over time ,and most especially the year after WWII, Usheiba moved the practice of Aikido away from using Atemi. (I am not an Aikido-ka, most of the information on which I base this came from my reading the Aiki Journal over the years.)
When the English translation of “Budo” was published there were Japanese Aikido instructors in Europe that reportedly forbid their students from purchasing this book because it showed clearly the use of Atemi with the Aikido techniques and the ‘modern’ Aikido had moved away from this practice. In fact the vast number of techniques Usheiba showed were done with Atemi accompaniment.
Whether this is still the case I do not know. However as the following photos demonstrate striking was a part of Usheiba’s art. I do not see there is a difference between the strikes in karate, to those used in Aikido. They seem to most often be used to break the attacker’s conceration allowing the Aikido response.
Also from Aiki Journal http://traditionalaikido.eu/doc/atemi_and_takemusu_aikido.pdf
Atemi in aikido is a controversial topic.. And yet it is clear that the ethical basis of aikido forces us to evaluate atemi
as something more than simply delivering a high impact blow to another’s human being’s body:
'The Way of the Warrior has been misunderstood. It is not a means to kill and destroy others. Those who seek to compete and better one another are making a terrible mistake. To smash, injure, or destroy is the worst thing a human being can do. The real Way of a Warrior is to prevent such slaughter
— it is the Art of Peace, the power of love'.
(Morihei Ueshiba speaking of a vision of the "Great Spirit of Peace" in 1942, during World War II, as quoted in Adjusting Though Reflex : Romancing Zen (2010) by Rodger Hyodo, p. 76).
So how can we understand atemi and it’s place within the practice of aikido?
Basically we can understand atemi at three levels:
#1. Lethal contact atemi as a technique in itself which decisively ends an encounter by rendering an opponent unconscious, crippled or dead.
#2 Non lethal but painful atemi used to create distraction or distortion in opponent’s body.
#3. Non contact atemi which is used to create an opening in an opponent’s defensiveness thereby allowing for the application of a technique which neutralizes him without further injury.