Despite President Donald Trump’s optimism over overtures from North Korea, experts on Wednesday urged caution toward a country with a long history of duplicity.

Trump told reporters outside the White House that he had received a “tremendous” letter from North Korean leader Kim Jong-un.

“We’re making tremendous progress with respect to North Korea,” he said.

“Prior to becoming president, it looked like we were going to war with North Korea. And now we have a lot of progress. We’ve gotten our prisoners back,” he said.

“We’re getting our remains [of soldiers from the Korean War] back. They continue to come in. A lot of tremendous things.”

In a meeting with South Korean President Moon Jae-in (pictured above right), Kim (above left) offered to dismantle the Yongbyon nuclear complex — and allow outside inspectors — in exchange for corresponding measures.

But Bruce Klingner, a Korea expert at the conservative-leaning Heritage Foundation, told LifeZette that the Trump administration should not overinterpret the gesture.

“I’ve been doing North Korea for 25 years,” he said. “I tend to be a bit cynical and skeptical.”

Klingner said the offer represents “no real progress” on the ultimate aim of persuading North Korea to give up its nuclear arms and its capacity to make them.

He said the North Korean regime has made similar offers in the past.

Who do you think would win the Presidency?

By completing the poll, you agree to receive emails from LifeZette, occasional offers from our partners and that you've read and agree to our privacy policy and legal statement.

The standard operating procedure is for North Korea to demand concessions up front with a promise to follow through on its commitments down the road, Klingner said.

“Denuclearization is always at the very end, almost as an afterthought,” he said.

Gordon Chang, author of “Nuclear Showdown: North Korea Takes on the World,” told CNN that Kim deserves an opportunity to do the right thing.

“But we didn’t really see any breakthrough promises here, because the promises that he made — which are steps forward — are, nonetheless, reversible and don’t really show a change of intent,” he said. “This is [the] Kim family playbook being played out again.”

Chang said the sticking point likely is to be what North Korea means by corresponding measures on the part of South Korea and the United States.

“This is Kim Jong-un saying, look, he’ll give up his Yongbyon nuclear complex if the United States takes those corresponding measures,” he said.

One expert said the United States must be more aggressive in punishing Russia and China for evading sanctions.

“Those were not specified. And Kim is going to ask for a lot. He’s going to ask for too much. I think that this was sort of euphoria-creating words from Kim, which the Kim family is really good at doing.”

Trump, however, struck an optimistic tone. He noted that North Korea has held off on tests of its nuclear arsenal and its long-range missile program since his summit with Kim in June.

“Prior to my coming into office, a lot of people thought we were going — it was inevitable — we were going to war in North Korea,” he said. “And now, the relationships, I have to tell you, at least on a personal basis, they’re very good. Very much calmed down.”

Related: Pence Hits Press for Dissing Return of Dead GIs’ Remains from North Korea

But Klingner, who was the CIA’s deputy division chief for Korea from 1996 to 2001, said the United States should not make any upfront concessions. He said Kim already had failed to deliver anything concrete after Trump canceled joint military exercises with South Korea earlier this year.

Klingner said Trump has not enforced sanctions against every North Korean entity. He said the United States also must be more aggressive in punishing Russia and China for evading sanctions.

He said Congress had identified 12 Chinese banks doing business with Pyongyang, for example.

“The ‘maximum pressure’ policy never was maximum, and it’s not in place,” he said.

Check out this video: