A tactic used as part of the SDS strategy to optimise the use of weapons and sensors by selecting high value targets for engagement by the defence while temporarily allowing less important targets to pass. This strategy forces the offence to attack with several times as many RVs as the defence has interceptors. Since preferential defence demands precise impact point prediction, the strategy is placed at a disadvantage if targets are closely spaced, if RVs can manoeuvre or if the defence intercepts ICBMs in the boost phase.