Former CENTCOM Commander Gen. David Petraeus [Ret.], told "Your World" Monday how differences in munitions between Western and Eastern countries is hindering the United States' ability to support Ukraine in its war against Russia.

The onetime CIA director told host Charles Payne Americans want to supply a "great deal more" resources to Ukraine, but that it is a challenge because of the difference in ammunition.

"The challenge is that we do not have the ammunition that they need -- it is Eastern Bloc ammunition. Their artillery shoots 152mm Howitzer ammunition. We shoot 155mm," Petraeus said. 

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Russian troops fire howitzers during drills in the Rostov region during a military exercising at a training ground in Rostov region, Russia. (Russian Defense Ministry Press Service via AP, File)

Russian troops fire howitzers during drills in the Rostov region during a military exercising at a training ground in Rostov region, Russia. (Russian Defense Ministry Press Service via AP, File) ( )

"That's why we're providing the Howitzers and then also tens of thousands of rounds to go with it because their artillery won't go into it," he added.

"Same with tanks and with fighting vehicles. So anything that we provide that would require a lot of spare parts, a lot of different ammunition and so forth.'

Petraeus added that the U.S. is working with allies in Eastern Europe to help facilitate transfer of ammunition and weapons that the Ukrainians already deploy and can use.

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Volodymyr Zelensky

Volodymyr Zelensky (Photo by Behrouz Mehri - Pool/Getty Images)

"The Western European and U.S. arsenals just don't have those items in them," he said.

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Of the controversial situation involving MiG-29 fighter jets that President Biden declined to greenlight the transfer of, Petraeus said that he wished "they could have just been quietly handed to the Ukrainian pilots at some airfield in Eastern Poland, and no one would make a big deal about it."