Secretary of State John Kerry accused former NSA-contractor Edward Snowden of helping terrorists, telling George Stephanopoulos on "Good Morning America" today that people have been placed in danger because of Snowden's revelations.

"We have evidence that people are in additional danger because operational security has been breached, because terrorists have learned firsthand about methods and mechanisms by which the United States collects intelligence," he said, never clarifying who specifically is at risk.

WATCH: US Has 'Evidence That People Are in Additional Danger'

Snowden is responsible for the largest security breach in U.S. history, leaking thousands of classified documents to the public. He now lives in exile in Russia and told NBC News he was trained as a spy.

Kerry said Snowden's actions have damaged U.S. intelligence gathering. "Our operations have been compromised," he said.

Kerry also vigorously defended President Obama's decision to withdraw all U.S. troops from Afghanistan by 2016, calling Republican opposition to the plan part of "an industry of automatic opposition to anything."

WATCH: Edward Snowden Reveals He Was International Spy

The secretary of state said everything the administration set out to do in Afghanistan five years ago has been accomplished and reiterated the time is now right for a draw down.

"When President Obama came in there was no policy," Kerry said. "The president increased the troops, put a policy in place and set a deadline for the Afghans to be able to take over security and, guess what? They met the deadline."

Kerry would not call the withdrawal a victory, but said that handing over the security of Afghanistan was the best option for the United States.

"This is their country. They have to want to fight for it," he said. "They have to be prepared to fight for it. And right now they are."

But with continued violence in the country and analysts' warning that parts of the country risk slipping back into Taliban and al Qaeda control, Kerry said the administration is prepared to "do whatever is necessary to protect the United States of America."

Asked about the Nigerian military chief claim that the government knows the whereabouts of the more than 200 school girls who were kidnapped in Northern Nigeria more than a month ago, Kerry said the United States has no information to verify the claim. He said U.S. personnel on the ground continue to work with the Nigerian government and he remains hopeful that the girls will be found and returned to their homes soon.

(Jacquelyn Martin/AP Photo | Barton Gellman/Getty Images)