Who's to blame for Rwanda?

The Rwandan genocide, like other genocides, is the responsibility of everyone who knew about it. The people directly committing the genocide are probably the guiltiest, because it was their idea. They were the ones who decided to eliminate countless innocents based on their prejudice, and actually went about killing them. However, the people who knew about it and did nothing are also partially to blame. This is because many countries who knew about it had the ability to stop the genocide or at least save more people, but chose not to in the interest of cost and the lives of their soldiers. Also, through inaction, they are almost encouraging more genocide because they prove the international community is unwilling to act and won't stop others from doing the same.