U.S. Air Force Chief of Staff Gen. C.Q. Brown Jr. is warning that the military must change if it wants to stay ahead of China and Russia, stating the "threat we were up against is not the threat we'll see in the future."

In an interview with Voice of America (VOA), Brown said "our adversaries have continued to advance their capabilities at the same time we’ve been using some of the same capabilities we’ve been using for the past 30 years."

Because of that, Brown said "we've got to change."

One change coming to the Air Force will be unveiled on Dec. 2 when the branch reveals its new B-21 stealth bomber, which will replace the B-1 and B-2 bombers that have been around since the 1980s.

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Air Force members stand in front of a B-1 bomber

Secretary of Defense Lloyd Austin and South Korea's Minister of National Defense Lee Jong-sup pose for a photo in front of a B-1 bomber during a visit to Andrews Air Force Base, Md., Thursday, Nov. 3, 2022. (Mandel Ngan/Pool via AP)

Brown said he could not provide the availability rates for the new aircraft because of classification concerns, but he said modernizing ensures "we have a ready force."

"One thing I will say is that this is why I'm going to modernize, because we have some aircraft that are, from a maintenance standpoint, are a little harder, more difficult to maintain [with] diminishing resources for parts," Brown said.

Last month, the Biden administration released its national defense strategy, which listed Russia as an "acute threat" and China as a "pacing challenge" and the greatest threat to national security.

According to the document, China has more active duty military personnel than the U.S. and has spent decades advancing its weapons, even adding new aircraft carriers, new fighter jets and a massive missile arsenal within the past few years.

Despite China's advancement, Melanie Sisson, a defense analyst with the Brookings Institution, told VOA that the U.S. is still "very, very capable" and "the best military force in the world."

View of Pingtan Island, mainland China's closet point to Taiwan

General view of the sea from Pingtan Island, one of mainland China's closest point from Taiwan, is pictured in Fujian province on August 4, 2022. (HECTOR RETAMAL/AFP via Getty Images)

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Though the U.S. has shifted its focus to China and Russia, Brown told VOA maintaining a strong relationship with allies in the region and leveraging growing U.S. capabilities, like space-based systems, will be key moving forward.

Last month, Brown visited partners in Ecuador, Peru and Colombia to discuss each country’s modernization efforts within their militaries, and this month he is scheduled to travel to Jordan, Qatar and the UAE for the same purpose.

China and Russia are looking to gain influence in the Western Hemisphere as non-NATO ally Argentina expresses interest in new fighter jets. Officials in the country are reportedly interested in China and Pakistan’s JF-17, the United States’ F-16s, India’s Tejas, and the Russian-made MiG-35.

USAF Thunderbirds F-16 jets perform in California

U.S. Airforce Thunderbirds, Lockheed Martin F-16 fighting falcons perform at Pacific Airshow on Saturday, Oct. 1, 2022 in Huntington Beach, CA. (Irfan Khan/Los Angeles Times via Getty Images)

VOA said a retired senior military official learned Argentina wants American-made fighter jets, but an arms embargo issued by Great Britain in 1982 could block the deal since the British make a few components of the F-16.

The official is reportedly concerned that the embargo could push Argentina to turn to China for its defense needs.

China and Pakistan's JF-17 jet takes flight

PAC JF-17 Thunder multirole combat aircraft, a fighter jet made in China and Pakistan. (Nicolas Economou/NurPhoto via Getty Images)

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Asked about this concern, Brown said the U.S. "was going to pay attention to it."

"My real focus is to ensure that we remain interoperable to the best of our abilities with our partners and have them understand that the United States and the United States Air Force is committed to working very closely with him," he said.