U.S. President Donald Trump said Iran is facing serious trouble, noting that protesters appear to be taking control of cities that few believed could fall just weeks ago, adding that the situation is being closely monitored.

Trump reiterated his warning that if Iranian authorities begin killing people as they have in the past, the United States would intervene and strike Iran “very hard where it hurts,” emphasizing that such action would not involve boots on the ground but would still be severe.