Trump warns Iran to stick to nuclear deal, but says he'll be 'surprised' if it does

US President Donald Trump.
Artur Widak | NurPhoto | Getty Images

President Donald Trump warned Iran on Tuesday to adhere to terms of a nuclear deal with world powers or "there will be big, big problems" for Tehran.

At a rally in Youngstown, Ohio, Trump said Iran has been emboldened by the nuclear deal, but "that won't take place much longer." He did not provide specifics.

But in an interview with the Wall Street Journal, the president said he would be "surprised" if Iran were in compliance with the nuclear deal when re-certification comes up again in three months.

—CNBC contributed to this report.