Andrew F. Krepinevich Jr.

As Western defense budgets are declining, the price of projecting power is increasing and the range of interests requiring protection is expanding. To square this circle, the Pentagon needs to embrace a dramatic shift in its strategy. It should turn its focus away from repelling traditional cross-border invasions and pursuing regime change followed by stability operations -- and concentrate instead on assuring access to key regions and the global commons.

Iran's acquisition of a nuclear bomb would upend the Middle East. It is unclear how a nuclear-armed Iran would weigh the costs, benefits, and risks of brinkmanship, meaning that it could be difficult to deter Tehran from attacking the United States' interests or partners in the region.

The military foundations of U.S. dominance are eroding. In response, Washington should pursue new sources of military advantage and a more modest grand strategy.