Transcript for Trump: 'The United States will withdraw from the Iran nuclear deal'

The Iran deal is defective at its core. If we do nothing. We know exactly. What will happen. In just a short period of time the world's leading state sponsor of terror. Will be on the cusp of acquiring. The world's most dangerous weapons. Therefore. I am announcing today that the United States will withdraw. From the Iran nuclear deal. In a few moments I will sign a presidential memorandum. To begin reinstating US nuclear sanctions. On the Iranian regime. We will be instituting. The highest level. Of economic sanction. Any nation that helps Iran and its quest for nuclear weapons. Could also be strongly sanctioned by the United States America will not be held hostage. To nuclear blackmail. We will not allow American cities to be threatened with destruction. And we will not allow our regime the chants death to America. To gain access to the most deadly weapons under. Today's action. Sends a critical message. To United States no longer makes empty threats. When I make promises I keep that.

This transcript has been automatically generated and may not be 100% accurate.