A powerless U.N, a simple target for attacks
Yesterday attack to U.N office in Iraq has many meanings within it; the first meaning comes when we look at the policy of U.S government towards the organization. In the process that ended with April war in Iraq the American government had completely ignored U.N and acted almost against it.
After the war they continued to ignoring U.N and had managed the situation their own way. This is the first time in the past 50 years that the whole organization with its long authorities becomes a useless body that not only can't prevent a war but also can't protect its own fate against threats coming from a super power. So it is not beyond expectations that nobody cares for it from now on.
The other reason one can find for an attack such as this is the danger of U.N becoming an unpaid agent for the same super power; coming to the scene after conflict is over and aiding them to shift their responsibility to the other countries and get free soon for their next action against some other country.
We can't think of terrorism without mentioning the motives of those who we think are responsible for that. And these motives are created by act of the people that cry most of the time against terror and terrorism.