A former deputy Defense Secretary under President Trump Donald John TrumpBiden on Trump's refusal to commit to peaceful transfer of power: 'What country are we in?' Romney: 'Unthinkable and unacceptable' to not commit to peaceful transition of power Two Louisville police officers shot amid Breonna Taylor grand jury protests MORE on Wednesday called plans to end war games with South Korea a "pretty substantial concession" to North Korean leader Kim Jong Un.

Robert Work, who previously served in the Pentagon under both Trump and former President Obama before his departure last July, told The Daily Beast in an interview that Trump's decision could embolden U.S. rivals and bring little in return.

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“Given that there were no really concrete concessions on the side of the North Koreans, I’m saying, wow, this was a pretty big concession to make without any conditions or any expectations of some type of concomitant North Korean concession," he told the website.

“If I was a Chinese or a Russian strategist, any time that I could get the United States to stop exercising near my national territory, I would think that would be a good thing."

Work added that the decision was likely "reversible" if North Korea failed to follow through on dismantling its nuclear program.

“On the other hand, if you’re going to try to convince North Korea that the administration’s approach is quite different from the past,” Work added, “this is one of the things that is pretty reversible. If North Korea begins to stall or not make any forward momentum, this is something you could turn back on rather quickly.”

The U.S. has engaged for years in semiannual war games with South Korean forces meant to simulate an invasion of North Korea, which the Trump administration says will come to an end absent future provocations from North Korea.

Trump dismissed claims from critics that he emboldened or conceded ground to Kim Jong Un during his meeting Tuesday. He has also praised the mainstream media for what he viewed as largely positive coverage of the historic summit.

"You know, it was sort of interesting because I noticed some of the press ... And I'm not even knocking them, because honestly they've been treating me very good on this subject. What's to treat badly? But some of the press would say, 'he's meeting with them, therefore he had a major loss.' I said, 'since when?' " Trump told Fox News's Sean Hannity.

The president returned from the one-day meeting with Kim early Wednesday, and is expected to host the North Korean leader in Washington D.C. at a later date.