WASHINGTON -- US President Donald Trump wasted the best chance to denuclearize North Korea by agreeing to meet with North Korean leader Kim Jong-un, former US Secretary of State Rex Tillerson said.

Tillerson also argued the US is now in a "worse place" in terms of national security because of Trump.

"Nothing worked out. We squandered the best opportunity we had on North Korea. It was just blown up when he took the meeting with Kim," the former secretary of state said in a recent interview with US magazine Foreign Policy, published Monday.

"We're in a worse place today than we were before he (Trump) came in, and I didn't think that was possible," said Tillerson.

Trump has held three bilateral meetings with Kim, starting with the first-ever US-North Korea summit in Singapore in June 2018.

The outgoing US president claims his meetings have prevented what would have been a nuclear war with the North, but is criticized by many for giving international recognition to Kim, which he had long desired. but getting little or nothing in return.

Denuclearization talks between the US and North Korea have stalled since the second Trump-Kim summit, held in Hanoi, ended without a deal in February 2019.

Tillerson served as Trump's first state secretary before he was fired in March 2018.

The former secretary said he did not understand the rationale behind Trump's meeting with Kim or his friendly relationship with other dictators such as Russian President Vladimir Putin.

"The only rationalization I could come to was that he thought, 'Well, if I disparage my allies and treat these bad guys as my friends, I'll get more done with them in US interests,'" he was quoted as saying.

"Maybe he thought, 'I'll let Kim know we're big buddies, and he'll give up his nuclear weapons,'" added Tillerson.

He went on to claim that many of Trump's foreign policy decisions may have been "uninformed" at best.

"His understanding of global events, his understanding of global history, his understanding of US history was really limited," said Tillerson. "I'm not sure many of those decisions were well informed."

Last week, while speaking to the Eighth Congress of the North's ruling Workers' Party, Kim said the North's external political activities must be focused on bringing its archenemy, the US, to its knees. (Yonhap)