“It is certainly worth a discussion, there has been a discussion and debate in the past over the use of contractors in other parts of our government,” Carney said.

But he noted that private contractors were “subject to the same system of checks and security procedures” as government workers. He also noted that contractors took the same oath to protect the Constitution as government employees.

“Whether it's a private contractor or a government employee, the issue of classified information and the obligation that individuals who take an oath to protect it have is the same,” Carney said.

Carney also noted that “contractors have long been involved in both our defense and intelligence efforts.”

The use of defense contractors has long been controversial. During the Iraq war, Democrats frequently criticized the use of contractors, noting that at times during the campaign the number of private American employees surpassed those of American military members.

The New York Times reported earlier this week that Snowden's employer, Booz Allen, held government contracts totaling $3.85 billion in 2011, representing 98 percent of its revenue.

On Tuesday, the company announced that it had terminated Snowden for “violations of the firm's code of ethics and firm policy.”

Booz Allen also noted that Snowden's annual salary was $122,000, lower than the $200,000 figure reported by The Guardian.

“News reports that this individual has claimed to have leaked classified information are shocking, and if accurate, this action represents a grave violation of the code of conduct and core values of our firm,” the company said in a statement. “We will work closely with our clients and authorities in their investigation of this matter.”