With Russia's military stockpile quickly depleting in its war with Ukraine, Moscow has been courting Iran and North Korea to help restock its supplies, a senior U.S. military official said Monday.

Iran has supplied Russia with drones that Moscow has used to target Ukraine's energy sector. But the official told reporters Monday that Russia might be trying to get more from Iran and strike a deal with North Korea for help.

"Russia, has been seeking to get additional capabilities from Iran," the official said. "And you know, the [National Security Council] put out a fair amount of information on this last week. You know, in a lot of ways, given this current state of Russia's munitions stockpile, it's not surprising that they continue to look at opportunities to work with countries like Iran and with – and North Korea to try to gain additional capability."

The city of Bakhmut in Ukraine's eastern Donbas region is seeing some of the most intense fighting since Russia's invasion began in February. Russia has made incremental gains in trying to take the city, but Ukraine is holding its ground.

The conflict, however, is showing the strains in Russia's ability to replace its munitions faster than it uses them up.

Director of National Intelligence Avril Haines said Dec. 4 during the Reagan National Defense Forum in California that Russia is burning through its military stockpiles "quite quickly."

"It's really pretty extraordinary," Haines said. "Our own sense is that they are not capable of indigenously producing what they are expending at this stage. That's why you see them going to other countries effectively to try to get ammunition."

In September, North Korea reportedly denied it was supplying Russia with any military aid. But in November, CNN reported National Security Council spokesman John Kirby accused North Korea of covertly supplying artillery shells to Russia through third-party nations. Kirby said it was unknown whether the shells were delivered and added any such aid would not have a significant effect in tilting the war in Russia's favor.

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