By appointing John Bolton to replace Gen. H.R. McMaster as his national security adviser, President Trump is giving himself the benefit of support from a tough-minded expert who knows how to work the system constructively.

Trump is at turns creative and destructive. Bolton can be expected to steer him toward the former and away from the latter. The new national security adviser is as blunt as his boss, so although he respects both process and the chain of command, he will give the president his unvarnished opinion and the benefit of his considerable knowledge and intellect.