Invading Iraq, when Iraq did not attack us, would seem to be initiating violence. Does that mean that there are exceptions to your premise? We can initiate violence if it contributes to our security or economic stability or whatever - and that violence is experienced by innocents who are acutely aware of what is happening and must deal with the tragic results. The vast majority of abortion decisions are carried out when the fetus is virtually unaware of this world and will not experience the horror and consequences of a war.
Just to be clear, that does not justify abortion. The invasion of Iraq was not justified either. I wish that religious people obsessed with abortion would have focused at least as much thought and energy on our initiation of violence half way around the world.
Just to be clear... I am not obsessed with abortion and will gladly continue try to answer your questions.