[en] In connection with the interpretation of the Bohm-Aaronow effect, the paper discusses the principle of interaction locality in quantum theory. Within the framework of nonrelativistic quantum mechanics, the principle is formulated in terms of Heisenberg equations of motion for the coordinate and velocity operators. The equations contain only electromagnetic field strengths and do not contain any potentials. They indicate that motion is affected by forces when the distance from the packet centre to the force region is less than the root-mean-square size of the wave packet, even if the wave function in this region is negligibly small