Outgoing CIA Director John Brennan said on Sunday that President-elect Donald Trump lacks “a full appreciation” of the implications of lifting sanctions on Russia and should be “very very careful” when it comes to policy on the matter.

In an interview on “Fox News Sunday,” Brennan said that Trump “has to be mindful” of the context for U.S. policy regarding Russia.

“Do you think that Mr. Trump understands the threat from Russia?” Fox News host Chris Wallace asked.

“I don’t think he has a full appreciation of Russian capabilities, Russia’s intentions and actions that they are undertaking in many parts of the world, and that’s what the obligation and responsibility of the intelligence community is,” Brennan said.

“Are you concerned when you hear Mr. Trump in that interview with the Wall Street Journal already talking about a situation where he might lift sanctions?” Wallace asked.

“I think he has to be mindful that he does not yet have a full appreciation and understanding of what the implications are of going down that road, as well as making sure he understands what Russia is doing,” Brennan replied.

“What are the implications of going down that road?” Wallace asked.

“Well, when we look at what’s happening in Ukraine, and what’s going on in Syria, and what there is happening in the cyber realm, I think Mr. Trump has to understand that absolving Russia of various actions it has taken in the past number of years is a road that he, I think, needs to be very very careful about moving down,” Brennan said.

In an interview published Friday in the Wall Street Journal, Trump said that he would consider lifting sanctions on Russia.

“If you get along and if Russia is really helping us, why would anybody have sanctions if somebody’s doing some really great things?” he told the Journal.

Watch their exchange below, beginning at 7:23: