WASHINGTON (AP) -- As U.S. defense secretary, Ashton Carter would face a daunting pile of problems at home and abroad. And then there are the unforeseen crises.
His confirmation hearings before the Senate Armed Services Committee are scheduled to begin Wednesday. A sampling of the top issues facing the 60-year-old Carter, who served in the Pentagon under President Bill Clinton and was deputy defense secretary in 2011-2013:
Among the toughest problems Carter would inherit is the war against the Islamic State group in Iraq and Syria.
The bombing of IS targets in Syria, which began in September, probably will continue well into Carter's tenure and maybe beyond. But he may face a more rapidly changing situation on the ground in Iraq, where the U.S. now has about 2,500 troops.
The Iraqi government wants to launch a major counteroffensive to regain lost territory, particularly the northern city of Mosul, but it is unclear whether Iraqi troops can succeed without U.S. soldiers by their side to call in airstrikes. Carter may have to decide in coming months whether to recommend to President Barack Obama that he authorize U.S. troops to perform that role.
Carter also would manage, and assess the effectiveness of, a program designed to train members of the moderate Syrian opposition.
Obama decreed that America's combat mission in Afghanistan is over, but there are more than 10,500 U.S. troops on the ground and many are still conducing counterterrorism operations against the Taliban and other insurgents.
American and coalition forces continue to train and advise the Afghan military. Obama has said that the U.S. can continue to provide ground and air support to the Afghan forces when needed.
Carter will have to deal with nagging questions about the pace of the U.S. withdrawal from Afghanistan, which under current plans would have all U.S. troops out by the end of 2016. Afghan officials are worried about the reduction in U.S. troop support.
U.S. military commanders say they will wait until after this summer's fighting season to decide if they should request any changes to the current drawdown. Any change to the pace could be seen as Obama reneging on his promise to end the war.
The U.S. is relying on NATO partners to help pressure Russia to relent in its support of anti-government rebels in eastern Ukraine -- a problem that aligns with Carter's long history of advocating for closer NATO ties to Ukraine.
Carter would be expected to weigh in on the question of whether to expand U.S. assistance for Ukraine to include weaponry.
Carter's background also fits another Russia problem: Moscow's reluctance to continue with a decades-long U.S. program to help secure surplus Russian nuclear materials to ensure they do not fall into terrorists' hands. Carter has focused on the problem of "loose nukes" in Russia since the collapse of the Soviet Union in 1991.
Improving defense relations with China is likely to rank as a Carter priority, in part because of tensions over Beijing's growing military might, regional influence and expanding cyberwarfare capability. Carter will have to key an eye on the other leading defense challenge in Asia: North Korea's nuclear weapons program.
HEALTH OF THE FORCE
After more than a dozen years at war, America's service members have battled more than enemy insurgents. At home, suicides, sexual assaults, traumatic brain injuries and post-traumatic stress all increased as the wars dragged on. Both suicides and reported sexual assaults increased last year, compared with 2013.
Associated Press writers Robert Burns and Lolita C. Baldor contributed.