U.S. Secretary of State John Kerry said Thursday it is likely that some of the billions of dollars in sanctions relief granted to Iran under a landmark nuclear deal will go to groups deemed terrorists.

Kerry said on the sidelines of the World Economic Forum that there is little the United States or others could do to prevent the now-unfrozen assets from getting into the hands of the Iran Revolutionary Guard Corps or "other entities" that Iran has supported in the past. But since nuclear-related sanctions were lifted on Iran last weekend, Kerry said there was no evidence yet to suggest such transfers had occurred.

"I think that some of it will end up in the hands of the IRGC or other entities, some of which are labeled terrorists," he told CNBC television in an interview. "You know, to some degree, I'm not going to sit here and tell you that every component of that can be prevented. But I can tell you this, right now, we are not seeing the early delivery of funds going to that kind of endeavor at this point in time."

Kerry also said that many critics of the Iran deal were inflating the amount of money that Iran now has access to. He said estimates of $100 billion to $150 billion were incorrect — $55 billion was more accurate, he said — because large chunks of that money is obligated to satisfy foreign debt.

In addition, he said Iran has more than $500 billion in infrastructure and development needs and must invest at least $100 billion to modernize its energy sector.

Earlier Thursday, Kerry rejected Iranian criticism of Washington's use of economic sanctions, saying they are imposed when appropriate.

Kerry said U.S. penalties against Iran and other nations have been "used judiciously and effectively" and will continue to be used in the future.

"We have made it very clear that we use sanctions when we think they are appropriate in order to counter behavior that we believe has broken the law or has challenged the United Nations Security Council or threatened the United States and we stand by our sanctions," Kerry told reporters.

"We think they have been used judiciously and effectively and we are looking to move on now to put to test the willingness of Iran and other countries in the region to try to reduce tensions and move in a different direction."

His comments came in response to a complaint lodged a day earlier by Iranian Foreign Minister Mohammad Javad Zarif who told The Associated Press in an interview that new U.S. sanctions over Iran's ballistic missile testing are "illegal" and an example of an American "addiction to coercion." The penalties were imposed Sunday, a day after the U.S. and other nations lifted sanctions over Iran's nuclear program.

"It shows that the United States has an addiction which has been very difficult for it to overcome," Zarif said. Washington, he said, suffers from an "addiction to pressure, addiction to coercion, addiction to sanctions."

U.S. officials say Iran's missile test in October violated U.N. Security Council restrictions on such activity.