(CNN) - The Iraq war is over and combat operations in Afghanistan end this year, but there's no evident peace dividend for the U.S. military.
Spending cuts from Washington budget deals have launched a transition started under former Defense Secretary Robert Gates to what he described as a leaner military shaped to deal with 21st Century challenges such as confronting terrorist-armed militias rather than full-fledged foreign armies.
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Now Defense Secretary Chuck Hagel also wrestles with the unrelenting budget pressures resulting from Washington's partisan dysfunction while also increasing the U.S. military footprint in Asia and Africa.
In addition, President Barack Obama has made clear his desire to reduce the U.S. nuclear arsenal as part of a broader global campaign against the proliferation of weapons of mass destruction.
Critics include conservatives who contend the United States is abdicating its role as the world's undisputed military power, while liberal supporters welcome moves to shift spending away from what they contend is a bloated and too big military to social programs and other government needs.
Unresolved issues include whether any U.S. troops will remain in Afghanistan past 2014. Afghan President Hamid Karzai has so far refused to sign a pact to keep U.S. forces in his country to help bolster security, and the Obama administration says no agreement means it will pull everyone out when the U.S.-led NATO mission concludes at year's end.
The uncertainty hinders planners already dealing with the budget constraints of forced spending cuts in recent years.
A 2014 budget passed by Congress eased some of the effects of the cuts known as sequestration, but Hagel and his generals still face further mandated spending reductions in coming years unless Congress also eases or eliminates them.
Meanwhile, the administration has set up a Marine contingent in Australia as part of its strategy to bolster U.S. influence in the Asia-Pacific region. U.S. military resources also have increased in Africa as part of anti-terrorism efforts and to provide another staging ground for possible needs in the volatile Middle East.