In a statement to CNBC, Dave Des Roches, an associate professor and senior military fellow at the US National Defense University, expressed "great concern" regarding US arms supplies to Ukraine, stating that, "Unless we have new production, which takes months to ramp up, we’re not going to have the ability to supply the Ukrainians."

Des Roches told the media outlet that during peacetime, the US weapons industry is only able to produce 30,000 rounds for the 155 mm Howitzer artillery weapons, while Ukrainian forces are burning through this quantity in around 2 weeks.

Read more: Ukraine announces more hefty weapons shipment to be expected from US

However, the US is not the only country facing this problem. Josep Borrell, the EU's high representative for foreign affairs and security policy, stated earlier that, "The military stocks of most [European NATO] member states have been, I wouldn’t say exhausted, but depleted in a high proportion, because we have been providing a lot of capacity to the Ukrainians," which was acknowledged by Chief of NATO, Jens Stoltenberg, that stated during the recent UNGA that alliance members must increase investment in their arms industry.

Stoltenberg, who held an exceptional meeting last Tuesday with the arms directors of the alliance to discuss means of restocking weapons of members, said in a statement to the New York Times that NATO members are now "working with industry to increase production of weapons and ammunition," calling for countries of the alliance to increase weapons orders in order to encourage manufacturers to boost capacity in the long term.

Read more: US weapons to Ukraine “in a big black hole” - US official

According to a report made by the Wall Street Journal last August, the war in Ukraine has reduced US military inventories of certain types of ammunition, as the US continues to supply Kiev with billions of dollars worth of weaponry. In turn, the US Department of Defense has been hesitant to replenish its arsenal, raising fears among US officials that the shortfall might undermine military readiness.

Citing US military sources, the WSJ revealed that Army Gen. Mark Milley, Chairman of the Joint Chiefs of Staff, has been reviewing the military arsenal on a monthly basis to see if the readiness levels are still suitable given the demand for ammunition in Ukraine. According to the authorities, the US last week sent Ukraine 105mm howitzer ammunition as a result of worries over its stockpiles of 155mm ammunition.

Read more: HIMARS are useless, Russia has "remarkably adapted": NYT

According to the WSJ, citing defense sources, the US has armed Ukraine with 16 HIMARS rocket launchers, hundreds of drones, missiles, and other weapons during the previous six months, a large portion of which, including the ammunition, has come directly from US inventories, depleting supplies intended for unforeseen threats.

In another report made by WSJ, widespread support for aid to Ukraine is dwindling in Washington, as House Republicans are questioning whether American taxpayers' money would be better spent either against China or the economic hardship that is facing the United States.

Read more: EU military support for Ukraine leaves the bloc 'vulnerable'