Globally, potential adversaries are building ever more complex, stronger, and deeper fortifications which are largely immune to the current United States weapons inventory. Advanced construction and design techniques coupled with technological improvements in mining have created a perfect storm of ultra-strong fortifications located at depths unreachable to all but the most distinctive and matchless weapon systems. A new domain is emerging which must be appreciated for its dynamic effect on policy, strategy and even national resolve. It is not a single adversary but rather a global problem enhanced through information sharing and parallel non-military applications. This issue requires a paradigm shift in the current U.S. strategic and operational approach for countering hostile nations willing to invest in the development of Subterranean Infrastructure and Fortifications (SIF). The U.S. must apply all elements of national power (Diplomatic, Information, Military and Economic DIME]) and commit itself to develop the capability to hold at risk the deepest targets from a full spectrum of delivery platforms. This will be no small effort. The hardest and deepest buried targets on the planet must be serviceable on an industrial scale. Rock, soil and concrete must be penetrated by sensors and weapons just as darkness and the skies have yielded to modern military technology. Failure in this task will grant our enemies control of a vital and emergent domain.