I guess that can be true, depending on which conflict you're talking about. For instance, we sell Israel weapons all of the time, and one can argue that their entry into Palestine was an "atrocity", however, I'm sure if we were bombarded by missiles as they were that we wouldn't hesitate to enter and clear out a small nation of terrorists either. Obviously their execution could use some work. We're not exactly experts at it ourselves, but war is far more complicated than what you see on TV.
I wouldn't describe Palestinian Territory as "a small nation of terrorists". If the US took an approach other than giving and selling arms (refered to as "aid" at times) to Israel meaningful peace negotiations might be possible.
The areas I specifically had in mind were places like Saudi and Bahrain. Arms sales to Bahrain were briefly restricted/stopped but resumed fairly quickly once news reels stopped appearing.