"I don't see that the president is always getting good advice," said Esper, who served under Trump during his first administration until Trump fired him in November 2020 after Esper objected to using the military during that year's riots.

Esper added, "I think Republicans on Capitol Hill have asked that same question: 'Is the president getting the best advice with regard to these strategic matters?'"

Regarding the memorandum of understanding with Iran, Esper said: "I like the fact that we've extended the ceasefire. I like the fact that the strait is being opened up; that will provide economic relief to a lot of people. And I like the fact that we're getting into nuclear talks."

But he added, "When I look at the MOU, there are many of the points that I have serious questions about and concerns about. So, you know, I think in many ways it's a wait and see. My principal concern has been that — it appears that too many of the incentives in my view have been given up front instead of later in the deal when we've seen much more progress on the nuclear aspects of whatever potential agreement comes from this."

The former defense secretary also noted that Tehran has learned from this war that it can effectively use closing the Strait of Hormuz as a threat.

Esper said the Iranians have seen that "they can shut down the global economy, that they can coerce the Arab Gulf States, even impose — even to threaten — the United States with regard to our military action. So in that way they have discovered that they have a tool that they can use, and that they are willing to suffer the pain, and that maybe we are unwilling to suffer more pain than what they are."

He added that "my other fear, my other concern, probably a reality, is that the Iranians have learned that they could survive the brunt of U.S. and Israeli military attacks. Despite how very successful they've been, the regime has been able to survive and withstand them. And that's going to embolden them, embolden them going forward."