That's a very good question and it is something the government is very concerned about accomplishing.
It's proven more difficult in certain departments than in others. But accrual accounting--and I'm speaking as a lay person in terms of accounting--is a much more effective mechanism for determining exactly what is spent in any one fiscal year. It in fact gives an honest and very clear answer as to how many dollars were actually expended in one fiscal year as opposed to simply, for example, buying a battleship in one year and putting all of the costs in that year and then not attributing it.
Mr. Smith can talk extensively about accrual accounting, more than I care to remember from time to time.