The United States military is studying the rate of munitions used in Russia's war in Ukraine to ensure that the Pentagon is accurately calculating the weapons it would need in case of any future conflicts or operations, the top U.S. general said on Tuesday.

Western officials have said that Russia has depleted a significant proportion of its precision-guided ammunition in its invasion of Ukraine and its industry cannot produce all kinds of ammunition and weapon systems due to Western sanctions.

Ukraine, which is being armed by Western countries, is also using artillery and other types of munitions at a rapid rate.

The United States military has contingency plans for potential conflicts around the world, that include how many troops, pieces of equipment and munitions could be required.

"We are going through a study, an analysis right now, to ensure that our war plans, our contingency plans, which we have multiples around the world in different theaters, to make sure that we've done the right math, the right estimates," Chairman of the Joint Chiefs of Staff General Mark Milley said at an event.

"We'll go back to industry to make whatever corrective action... to make sure that we do have appropriate stockage levels for something that might happen," Milley added.

The United States has said that North Korea is covertly supplying Russia with a "significant" number of artillery shells for its war in Ukraine.

Russia has also procured drones from Iran that have been used to attack cities and power infrastructure in Ukraine.