By Steve Holland

WASHINGTON (Reuters) – U.S. President Donald Trump struck a blow against the 2015 Iran nuclear agreement on Friday in defiance of other world powers, choosing not to certify that Tehran is complying with the deal and warning he might ultimately terminate it.

Trump announced the major shift in U.S. policy in a speech that detailed a more confrontational approach to Iran over its nuclear and ballistic missile programs and its support for extremist groups in the Middle East.

Trump said in an address at the White House that his goal is to ensure Iran’s never obtains a nuclear weapon.

“We will not continue down a path whose predictable conclusion is more violence more terror and the very real threat of Iran’s nuclear breakout,” Trump said.

While Trump did not pull the United States out of the agreement, aimed at preventing Iran from developing a nuclear bomb, he gave the U.S. Congress 60 days to decide whether to reimpose economic sanctions on Tehran that were lifted under the pact.

That would increase tension with Iran as well as put Washington at odds with other signatories of the accord such as Britain, France, Germany, Russia, China and the European Union.

Trump warned that if “we are not able to reach a solution working with Congress and our allies, then the agreement will be terminated.”

(Reporting by Steve Holland; Additional reporting by Makini Brice, Patricia Zengerle, Jonathan Landay, Warren Strobel and Arshad Mohammed in Washington, Andrea Shalal in Berlin, Dmitry Solovyov in Moscow, Parisa Hafezi in Ankara and Dan Williams in Jerusalem; Editing by Yara Bayoumy and Alistair Bell)