Have we? I don't think the UN is going to invade Iran over this, especially after it went so well the last time with the US. And sanctions for Iran are already at the "you don't get anything" level, i don't think they can be ramped up any more. Morally sure, people now believe this is wrong while in the distant past they may have not cared, but practically not much has changed. The best we can hope for is an organized resistance that other large nations can funnel money and arms to.
Strongly worded letters might not mean much, but at least they are on the right side of the issue, even if only symbolically.