Yesterday, President Donald Trump announced that the United States would pull out of the 2015 Iran nuclear deal. The agreement, negotiated by the administration of Trump's predecessor Barack Obama, lifted sanctions on Iran in exchange for restrictions on its nuclear program that would prevent it from developing nuclear weapons.

Juliette Kayyem, homeland security expert and CEO of Zemcar, criticized the move on Boston Public Radio Wednesday.

"There’s a tendency to say we 'withdrew' from the Iranian deal. We actually violated it," Kayyem said.

The treaty was endorsed by the U.N. Security Council, of which the U.S. is a member, but was not ratified by the U.S. Senate.

Kayyem said the Trump administration's abrupt move did not leave enough time to develop an alternative.

"So what is 'plan B?'" Kayyem asked. "I don’t think anyone knows right now, and that’s what makes everyone relatively nervous.”

Click the audio player above to hear more from Juliette Kayyem.