>When a situation is certain to develop in a particular way because decisions have been taken that cannot be changed
>A course of action has been finalized.
>An unalterable decision has been reached, or step taken. Source: theidioms.com
This expression comes from a Latin phrase (Alea iacta est) thought to have been said by Julius Caesar when he crossed the Rubicon river and became embroiled in civil war in 49 BCE.
>From the moment the negotiations failed, the die was cast and war was inevitable.
>After playing dirty politics which lead to the split of group, the trouble makers realized that the die was cast and they shall remain as a mute sepctators of the eventualities to follow.