ward off a danger

World leaders have discussed this warning capability for some time, but it was hard to take such an important step to ward off a danger that seemed, in previous years, to be hypothetical.

That political "constraint" has direct operational consequences, in terms for example of the choice of units and equipment to be deployed and the rules of engagement, in particular in the case of pre-emptive action to ward off a danger that has been identified but not yet materialised.