Perhaps I'm missing the distinction between refusing to tolerate lack of obedience on the part of Iran, being willing to do militarily, or otherwise, whatever is necessary to impose obedience on them on the one hand, and conquering them on the other. Rome would have considered such a posture towards another nation to be one of conquest. Rome didn't care if conquest was achieved by actual invasion or merely by its threat and, if by invasion, they didn't care if it was an invasion by Rome itself or by proxy. The end result, submission to the will of Rome, was all that was required for conquest to have been accomplished.
