I disagree. German tanks and airplanes need engines to move and are part and parcel of the whole killing of many innocent people. They knew what they were making and what it was for. It took making the powder, the cannon barrels, and myriads of parts to make these killing machines. The end result is the same, people were killed. Quiet relevant. But not so in this original thread.
How about we say they used people for killing machines? Is that relevant?