Beyond prudence, however, it is clear that without a major threat to generate consensus and to rally the country around defense and defense spending, the military posture of the United States will erode as the defense budget is cut. Hence, relying in the future on what is currently seen to be as sufficient force to be "decisive" could easily prove unachievable and the results problematic or worse for U.S. policy. The absence of a direct and daunting external security threat is, of course, a most obvious aspect of the difficulty in defining the future defense posture of the nation. The United States has long resisted maintaining a large standing military and the Cold War years could prove an aberration to that history. Extending this historical observation of small standing forces, it is clear that there is no adversary on the horizon even remotely approaching the military power of the former USSR. While we might conjure up nominal regional contingencies against Korea or Iraq as sensible planning scenarios for establishing the building blocks for force structure, it will prove difficult to sustain the current defense program over the long term without a real threat materializing to rally and coalesce public support. Allocating three percent or less of GDP for defense could easily prove to be a ceiling and not a floor. It should be noted that in Europe, defense spending is closing in on 1 to 2 percent of GDP. Ironically, as the Department of Defense seeks to come to grips with this new world, the structural limitations and constraints in how we develop systems and procure weapons based on current technological and industrial capacity for producing them will be exacerbated by downward fiscal pressure giving us little room for mistakes and flexibility. Air, land, space, and sea forces are currently limited in the actual numbers and types of systems that are available for purchase and more limited in that there are virtually no new major systems on the horizon. That could change. The M-1A-1 tank is in production only for foreign sales. Despite the allure of the Arsenal Ship, the Navy still has only four active classes of warships from which to replace its capability and, for the first time this century since aircraft entered the inventory, is without a new aircraft in development. The Air Force can be placed in similar straits if the F-22 program is deferred or canceled because of rising cost and fiscal constraints. Time will tell what happens to the Joint Strike Fighter. Assumptions about reliance on technology and R&D providing insurance policies for future defense needs may prove ill-advised if and as DOD is forced to cut back and reduce those programs even further. Indeed, over time, commercial R&D could become the main source for procuring software and other systems needed to upgrade today's weapons systems and for so-called "leap-ahead" technologies that may prove elusive to create.