It is possible for a Church leader to advocate the need for political change without supporting violent military action. John Paul II's position on the war was exactly the right one for a Roman Catholic leader.
It is not only possible but absolutely necessary for church leaders of every denomination to advocate non-violent change while that change is possible. A non-violent solution to the Iraq problem was simply not available, and we were already at war with terrorists, which Iraq harbored, trained and funded.
In June, our troops found a mass grave with 200 Kurdish children in it. They had been buried alive. Some were still holding their dolls. Sitting across a table from a man who would order that as a matter of course and making him see reason is simply not possible.