This morning I received a text message from a friend who was on her way to work. It read: "Am just in the tube and there's a really offensive poster up there but it says its Amnesty - do you know anything about it? It says 'Rape is cheaper than bullets'."
I quickly replied saying yes, it was an Amnesty International advertisement launched this week, and if it's offensive then that is nothing compared to what hundreds of thousands of women and girls are suffering in conflict zones around the world.
The new Bullet ads that are appearing across the London Underground network over the next few weeks are designed to make passengers stop and think about some of the real horrors faced by women and girls. They're meant to be provocative, because people are either immune or ignorant to the abuses that occur in global conflicts on a regular basis.
In previous and present wars, such as in Bosnia and eastern Democratic Republic of Congo, rape and sexual violence are regularly used, and frequently the perpetrators go unpunished.
In the DRC's troubled region of North Kivu, we are told that more than 2,200 cases of rape and sexual violence were reported in the first six months of 2008. Of these only 150 cases were heard in court, and in only one case was the perpetrator found guilty; that's one out of 2,200.
Sexual violence against women isn't unique to the DRC conflict.
The UN estimates that between 20,000 and 50,000 women were raped during the 1992-5 war in Bosnia and Herzegovina.
Systematic rape is a crime against humanity. Even one rape during conflict is in fact defined as a war crime, although it is rarely treated as such.
If authorities fail to investigate and prosecute acts of rape in wartime, it will have an impact on the stability of the region once the fighting has stopped. Rape can cause entire communities to flee in terror, freeing up land and resources that are being disputed and ethnically reshaping whole societies. It can also destabilise a community by destroying family units.
The women who are raped regularly suffer horrific brutality, mutilation and violation. Frequently they pick themselves up and carry on but they are usually abandoned, ostracised, stigmatised and blamed for the rape they have suffered.
Meanwhile men turn away from the women in disgust and shame and blame them for their rape, as their ability to protect their family is called into question.
The legacy lasts for years and across generations with the whole community irrevocably displaced, damaged and broken and unlikely to recover for a long time.
In fact this act can produce a similar result as the one that is sought through the use of conventional weaponry but at a much smaller financial cost.
Various resolutions passed at the United Nations Security Council have acknowledged the impact of sexual violence against women in conflict. But they mean nothing if they're not enforced on the ground.
More has to be done to protect these women from these atrocious acts. I'm hoping that over the next few weeks more people will be stirred into action by the Amnesty ad. After all, it's not the ad that's offensive - it's the truth portrayed that should offend us.