WASHINGTON - A top U.S. military official called North Korean leader Kim Jong Un “a man of his word” while backing up assertions by other key officials that talks with Pyongyang are making progress.

The commander of U.S. Forces-Korea, General Vincent Brooks, said that since North Korea’s last missile launch in November 2017, language and actions from Pyongyang have “signaled a change in direction, perhaps a change in calculus that we had been looking for.”

Brooks spoke Saturday to an audience at the Aspen Security Forum in Aspen, Colorado, via videolink.

U.S. President Donald Trump and Secretary of State Mike Pompeo have repeatedly expressed optimism about the ongoing talks with North Korea since Trump and Kim met in Singapore last month.

North Korean leader Kim Jong Un shakes hands with FILE - North Korean leader Kim Jong Un shakes hands with U.S. Secretary of State Mike Pompeo, May 9, 2018, released by North Korea's Korean Central News Agency in Pyongyang. FILE - North Korean leader Kim Jong Un shakes hands with U.S. Secretary of State Mike Pompeo, May 9, 2018, released by North Korea's Korean Central News Agency in Pyongyang.

On Friday, Pompeo said he and the president remained “upbeat” about the prospects that North Korea will move ahead with complete and verifiable denuclearization.

North Korea's Punggye-ri nuclear test facility is North Korea's Punggye-ri nuclear test facility is shown in this DigitalGlobe satellite image in North Hamgyong Province, North Korea, May 23, 2018. North Korea's Punggye-ri nuclear test facility is shown in this DigitalGlobe satellite image in North Hamgyong Province, North Korea, May 23, 2018.

?Boosting nuclear fuel?

Still, some in the intelligence community have voiced skepticism that Pyongyang can be trusted, and there are reports that rather than scale back its activities, the North Koreans have actually boosted production of nuclear fuel.

Satellite imagery and U.S. intelligence officials have also pointed to evidence of continued work at multiple secret sites across the country.

Brooks declined to confirm or deny those reports Saturday, and acknowledged the threat remains.

“We haven’t seen a complete shutdown of production yet. We have not seen a removal of fuel rods,” he said. “These types of things tell us there are still steps that must be taken on the road to denuclearization.”

But Brooks expressed hope those steps are in the works.

“To be sure, the physical threats and capabilities are still in place, but it’s evident in words and actions that the intent to use them has changed,” he said.

“[Kim Jong Un] has really demonstrated he is a man of his word in a number of ways,” Brooks said. “We will take him at his word.”

FILE - This photo released by Japan's Ministry of FILE - This photo released by Japan's Ministry of Defense shows what it says is the North Korean-flagged tanker Yu Jong 2, left, and the Min Ning De You 078 lying alongside in the East China Sea, Feb. 16, 2018. China says it is "highly concerned" about a reported ship-to-ship transfer on the high seas that could violate U.N. sanctions on North Korea. FILE - This photo released by Japan's Ministry of Defense shows what it says is the North Korean-flagged tanker Yu Jong 2, left, and the Min Ning De You 078 lying alongside in the East China Sea, Feb. 16, 2018. China says it is "highly concerned" about a reported ship-to-ship transfer on the high seas that could violate U.N. sanctions on North Korea.

?Some skepticism

Still, some in the U.S. are skeptical, waiting for additional proof North Korea and Kim have changed.

“I don’t think we ought to be making any concessions until they [North Korea] really start moving forward in a very strong, concrete, positive way to denuclearization, which I interpret to be they dismantle their nuclear capability,” the chairman of the House Homeland Security Committee, Republican Mike McCaul of Texas, said at the Aspen conference.

McCaul also echoed calls by top U.S. diplomats for stronger enforcement on sanctions against Pyongyang.

“This is not the time to be putting the brakes on maximum pressure,” he said. “This is a time be putting the accelerator on.”

Sue Mi Terry, a former senior CIA analyst, also voiced reservations that Kim can be trusted.

“I don’t see any sign that North Koreans have committed to denuclearization,” she said. “We don’t have a deal yet between United States and North Korea. We only have the Singapore declaration, which everybody knows is vague, is aspirational.”

VOA’s Margaret Besheer and Steve Herman contributed to this report.