As with Muslims after 9/11, do Xian's have a responsibility to speak out when abortion doc's are killed?

After 9/11 many people criticized Muslims for not denouncing in stronger terms the attacks (I don't agree with the criticism, but that's a separate issue). Regardless of where you stand on abortion, it is a legal procedure. Do Christians have an obligation to speak out when other Christians threaten or even kill abortion providers? Do prominent Christian leaders have a responsibility to publicly denounce such acts and do you think they are doing so to the degree that they should?