Senate hearings on whether to confirm Ashton Carter as President Obama’s pick to be the new defense secretary are set to begin next week, amid widespread, military-related challenges around the globe.

The hearings are scheduled to begin Wednesday in the Senate Armed Services Committee. If confirmed, Carter would replace Secretary Chuck Hagel, who announced in December 2014 that he would resign from the post when a replacement is confirmed.

Carter faces an array of challenges, with the unexpected problems emerging as among the most challenging.

U.S. troops are now back in Iraq, after the U.S. ended the war on terrorism in the Middle East country in 2011, this time trying to help the local militia defeat The Islamic State.

The violent extremist group has recently flourished in Iraq and has taken control of parts of the country.

In addition, the recent outbreak of the deadly Ebola virus in West Africa has required the unexpected and urgent deployment of U.S. troops.

Even predictable challenges, such as pursuing and killing terrorists in the Middle East and Afghanistan, can be harder than they seemed on the outside, even for an experienced national security practitioner like Carter.

The 60-year-old Carter is a seasoned but relatively obscure Washington national security expert. He was the country’s deputy defense secretary from October 2011 to December 2013, a role that is essential the agency’s chief operating officer.

If confirmed by the Senate, Carter would be Obama's fourth Pentagon chief in his roughly six-year administration.

The president nominated Carter in early December, just eight days after Hagel abruptly resigned under White House pressure, after less than two years on the job.

Carter also has extensive experience in the national security arena. Before he served as deputy defense secretary from October 2011 to December 2013 he was the Pentagon's technology and weapons-buying chief for more than two years.

During the administration of President Bill Clinton he was assistant secretary of defense for international security policy. Before that he was director of the Center for Science and International Affairs at Harvard University's John F. Kennedy School.

He has bachelor's degrees in physics and medieval history from Yale University and received his doctorate in theoretical physics from Oxford University, where he was a Rhodes Scholar. He has served on the advisory boards of MIT's Lincoln Laboratories and the Draper Laboratory. He has extensive knowledge of the inner workings of the U.S. nuclear arsenal.

In national security circles Carter is closely associated with a concept he and former Secretary of Defense William Perry championed in the 1990s. They called it "preventive defense." Its basic premise is that in the aftermath of the Cold War the U.S. could forestall major new security threats by using defense diplomacy — forging and strengthening security partnerships with China, Russia and others.

Carter's view of U.S. defense priorities appears to fit well with the Obama agenda, including better minding of defense alliances and partnerships in Asia and the Pacific, as well as more attention on cyber-defense and countering the spread of weapons of mass destruction.

The Associated Press contributed to this report.