Former Secretary of State Rex Tillerson delivered a damning verdict on Donald Trump in a new interview, saying the United States is in a worse place globally because of the outgoing president.

Tillerson, who Trump fired via tweet in March 2018 following a controversial 14 months leading the State Department, told Foreign Policy magazine this week that Trumps understanding of global events, his understanding of global history, his understanding of U.S. history, was really limited.

Its really hard to have a conversation with someone who doesnt even understand the concept for why were talking about this, said the former CEO of energy giant Exxon Mobil, who Trump replaced with Mike Pompeo.

Tillerson recalled having to constantly evaluate my last conversations with the president to figure out what he had engaged with the most.

I would try different approaches with him, he remembered. I used to go into meetings with a list of four to five things I needed to talk to him about, and I quickly learned that if I got to three, it was a home run, and I realized getting two that were meaningful was probably the best objective.

Tillerson said he would often take charts and pictures to briefings with Trump because I found that those seemed to hold his attention better.

If I could put a photo or a picture in front of him or a map or a piece of paper that had two big bullet points on it, he would focus on that, and I could build on that, he added.

A major impediment to getting things done were the people telling Trump untruths, leading him to form a view that had no basis in fact, said Tillerson. There were other people giving him information that was not accurate, every day, usually before I got to see him.

As for the U.S. standing in the world, Tillerson said nothing worked out, as Trump squandered opportunities with North Korea, China and Russia.

Were in a worse place today than we were before he came in, and I didnt think that was possible, he lamented.

Read Tillersons full interview with Foreign Policy here.