Senior defense officials face a host of critical issues when assessing the nation’s military posture. Most importantly, they are responsible for determining which threats the United States must be prepared to address, what capabilities will be required to do so, and how the US military should be organized, trained, equipped, and employed to counter these threats successfully if and when they materialize.

This backgrounder offers some preliminary observations on the likely characteristics of the new program, and raises several questions that the Army will have to address as it goes forward.

The United States currently faces a host of critical foreign and defense policy challenges, including the wars in Afghanistan and Iraq, instability in Pakistan and the reconstitution of an operational sanctuary for key elements of al Qaeda and the Taliban in parts of that country, Iran’s development of an indigenous uranium enrichment capability and perhaps a nuclear weapons program as well, a resurgent Russia that is increasingly authoritarian at home and assertive abroad, and China’s ongoing development and deployment of advanced military capabilities. In addition to managing these current conflicts and potential crises, the President and his advisors will also be responsible for decisions that will shape US defense strategy and force structure for years and possibly even decades to come. Because the dangers the United States now faces are so numerous and so demanding, one of the most critical tasks for the Obama administration will be to reassess and reshape America’s military alliances.

Over the past several years, the prospect of a terrorist group armed with a nuclear weapon has frequently been cited as a genuine and overriding threat to the security of the United States. Although the likelihood of a nuclear terrorist attack may be relatively low, the consequences of such an attack would obviously be enormous. There is, therefore, widespread agreement regarding the severity of this threat. Despite this consensus, a number of important questions remain open to debate: How real is the risk that a terrorist group could acquire or construct a functional nuclear device, and how might it attempt to do so? Which group poses the greatest threat in this regard, how has that threat changed over time, and is it currently growing or abating? What existing and prospective measures will prove most effective in preventing terrorists from obtaining a nuclear weapon, stopping them from delivering and detonating a weapon if prevention fails, and responding both at home and abroad in the event that an attack succeeds? The purpose of this report is to examine these critical issues.