According to administration officials, Pentagon official Ashton Carter is expected to be President Obama's nominee to replace Chuck Hagel as U.S. defense secretary. (Reuters)

President Obama's pick to lead the Pentagon, former deputy secretary of defense Ashton "Ash" Carter,  has been a big supporter of increasing the country's cybersecurity capabilities. His nomination signals that the administration is likely to continue to aggressively build out its ability to fight adversaries in the digital world.

Carter served as the deputy secretary of defense from October 2011 to December 2013 -- and before that spent two years as the Defense Department's chief weapon and technology buyer. He first joined the Pentagon as a civilian program and technical analyst in 1981, working on missile defense.

Carter has reportedly been influential in the reorganization of U.S. Cyber Command over the last few years. Last year, the Pentagon announced plans to grow the force fivefold in the coming years as it faces increasing threats of online attacks from other state-level actors. In October, some White House networks reportedly were compromised by hackers thought to be working for the Russian government. Chinese government hackers are suspected of being behind recent breaches at the United States Postal Service and the National Oceanic and Atmospheric Administration.

At an Aspen Security Forum in 2013, Carter called cyber security an area of "great importance" that the Defense Department was investing in despite budget cuts associated with sequestration. He also outlined the Pentagon's approach to cyber: defending the nation's government and private-sector networks while developing cyber capabilities to "nullify cyberadvantage on the part of others." This last part is essentially offensive cyber capabilities.

"It's a new field of warfare," Carter explained, noting that the Pentagon had to be cautious while determining how to proceed. "Obviously, we want to do things as we try always to do, in a way that is lawful and in a way that our population can support and is consistent with our values," he said.

Carter's prioritization of cyber security puts him in step with the Obama administration's focus on the issue. In 2012, the president signed a secret directive that reclassified some cyber actions previously considered offensive as defensive -- taking proactive action to disrupt perceived cyber threats.

At the Aspen forum, Carter suggested that society at large was "underinvested" in cybersecurity and that private companies needed to take more steps to protect themselves.  "A lot of our critical businesses are more vulnerable than they should be, and what should really happen is they should take the steps to harden themselves," he said. "And that's more important than us rendering aid, which, of course, we're prepared to do as we defend the rest of the country."

Carter comes from a science-heavy background: He has bachelor's degrees in physics and medieval history from Yale University and received his doctorate in theoretical physics from Oxford University.