MOSCOW, Sept 6 (Reuters) - U.S. intelligence has assessed that Moscow is buying artillery ammunition from North Korea, the New York Times reported, on the heels of reports that the Russian military has begun using Iranian-made drones.

U.S. government officials told the Times that the purchases showed sanctions had begun to bite and reduce Russia's ability to sustain its invasion of Ukraine, which Moscow has called a "special military operation".

The Times report on Monday said the recently declassified intelligence provided no details about what was purchased, beyond saying that the items included artillery shells and rockets. Russia was expected to buy more such gear, the Times reported.

Last month, a U.S. official told Reuters that Russia's Iranian-made drones had suffered "numerous failures". The official said Russia most likely planned to acquire hundreds of Mohajer-6 and Shahed-series unmanned aerial vehicles (UAVs).

Ukraine recently launched counteroffensives in several locations, including around Kherson, which Russia has occupied since early in the invasion. In preparation for those attacks, Ukrainian forces struck Russian supply areas, including those containing artillery and ammunition.

Officials have said Western sanctions are limiting Russia's ability to replace vehicles and weapons destroyed in Ukraine.