When we say national interests we immediately make it as a national security issue without thinking how we are going to pay for it and is the government really the one to define it as such. Since the government is made up of representatives of the people and they use public funds by way of taxation to spend it according to people's wishes. But we have seen that national security interests are not defined in much detail and if somebody tries to ask for much detail it is just said that it is in the best interest of the nation's security and it will be put in jeopardy if all the details are leaked to the public.
But now that this new economy has started to make us think about how to carry on our day to day business and this economy is not going to fundamentally change in the near or any future (by the way we are taking on debt), we should be starting to ask hard and tough questions about our absolutely necessary national interests abroad are and how we are going to pay for it. We will not be able to afford to defend unlimited national interests and it should be really crucial and even our long term interests may be damaged in order to qualify as a National interest.