He was responding to remarks by former Secretary of State John Kerry during Tuesday's proceedings at the Democratic National Convention.

"John Kerry and the JCPOA [nuclear deal] gave Iran $150 billion in sanctions relief. That was the Obama-Biden administration," O'Brien told host Martha MacCallum. "Iran spent that money not on its own people, not to build a middle class in Iran. They spent it on terrorist activities in Lebanon, and Syria, and Iraq, in Yemen, so the JCPOA was no great deal. In fact, it was the worst diplomatic deal since the Munich appeasement in 1938."

The Munich Agreement, reached by Nazi Germany, Great Britain, France and Italy allowed Hitler's troops to annex Czechoslovakia's Sudetenland and is remembered today as a classic case of diplomatic appeasement.

Trump withdrew the U.S. from the nuclear deal in 2018, provoking criticism from former advisors to President Barack Obama On Thursday, O'Brien indicated that the Obama administration had dropped the ball when it came to combatting ISIS in the Middle East.

"Secretary Kerry's comments were ironic in that ISIS was running a caliphate the size of Great Britain across Syria and Iraq when he left office," he said. "The Iran deal contributed to that. The precipitous withdrawal of American troops from Iraq precipitated ISIS, Americans were killed ... brutally executed by ISIS, and it took Donald Trump to bring justice to Baghdadi," he said, referring to former ISIS leader Abu Bakr al-Baghdadi.

"It took Donald Trump to destroy the ISIS caliphate."

Since the U.S. left the deal, Iran has denounced the U.S. and engaged in several provocations in the region. On Thursday, Tehran unveiled two new missiles, one of which was named after Gen. Qassem Soleimani, who was killed in an airstrike ordered by Trump earlier this year.