President Trump on Friday called the Iran nuclear deal "unacceptable," adding he considers the Iranian government the "world's leading state sponsor of terrorism."
"What is the purpose of a deal that only delays at best Iran's nuclear capabilities for a short time?" he asked at the White House. "This as president of the United States is unacceptable."
"Importantly, Iran is not living up to the spirit of the deal," Trump continued. "We will deny the regime all paths to a nuclear weapon."
"As I have said, the Iran deal was one of the worst and most one-sided transactions the United States has ever entered into."
Trump then announced he would decertify the Iran nuclear pact, adding that Congress must help decide how to proceed in regards to Tehran's nuclear program.
"I am announcing today that we cannot and will not make this certification," he said. "We will not continue down a path whose predictable outcome is more terror, more violence and Iran's preventable nuclear breakout."
President Trump makes a major announcement on the Iran nuclear deal.
President Trump on Friday will say that the Iran nuclear agreement is no longer in America's security interests, according to Secretary of State Rex Tillerson, other U.S. officials and outside advisers to the administration.
Trump will highlight specific faults in the pact during a speech that afternoon, they said, but will not withdraw from it or immediately re-impose sanctions on Iran.
The president will instead notify Congress he is "decertifying" the 2015 agreement, which is known as the Joint Comprehensive Plan of Action (JCPOA).
Trump will argue that although Iran is complying with the letter of the accord, the deal's details are not sufficient enough to be in America's best interests.
Tillerson said Trump's remarks will give Congress 60 days to decide whether to re-impose sanctions, modify the law or do nothing, with the first option effectively killing the accord.
Former President Barack Obama's administration spent 18 months working on a landmark global agreement over Iran's nuclear program before its creation in 2015.
The deal placed greater restrictions on Iran's nuclear energy capabilities in exchange for economic sanctions relief.
The Associated Press contributed to this report.