WASHINGTON — President Donald Trump said he will keep the U.S. military in Iraq, in order to keep a close eye on Iran, which is a "real problem," according to a CBS interview that will broadcast on Sunday.

Trump's decision to draw down military forces in the Middle East has been met with fierce criticism, and helped prompt the departure of James Mattis as Defense Secretary. But in an interview with CBS, the president suggested the U.S. would at least maintain a presence to keep an eye on Tehran.

"I want to be able to watch Iran ... all I want to do is be able to watch," Trump told CBS' "Face the Nation" adding that he was not planning a military strike on Iran.

"This is what a lot of people don't understand. We're going to keep watching and we're going to keep seeing and if there's trouble, if somebody is looking to do nuclear weapons or other things, we're going to know it before they do," he added.

Trump then explained that since the United States has spent a "fortune" on the Al Asad Air Base in western Iraq, which he made a surprise visit to in December, the U.S. will hold on to it.

"We have an unbelievable and expensive military base built in Iraq. It's perfectly situated for looking at all over different parts of the troubled Middle East rather than pulling up," he said.

In wake of a number of public differences he's had with intelligence officials regarding their assessments of threats to the U.S., Trump said he trusted them--but wouldn't always agree with what they said.