Japanese newspaper Nikkei reported on Wednesday that part of military joint drills between Japan's ground forces and US marines were canceled due to a lack of shells for the US HIMARS launching systems.

The Japanese Ministry of Defense stated that the HIMARS shells were not delivered to the training site for reasons related to the US side.

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

The news outlet added that HIMARS shells were not available during the exercises taking place in Hokkaido, eastern Japan, which were launched on October 1, resulting in canceling part of the drills that were supposed to enhance skills related to using the American HIMARS. As a result, the soldiers were only able to train on MLRS developed in Japan.

Japan's Ground Self-Defense Force (GSDF) and US marines are currently holding exercises over the span of 14 days north of Hokkaido Island to simulate, "the defense of remote islands."

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The Japanese Joint Staff announced in a statement that the bilateral exercise "further strengthens the deterrence and response capabilities of the Japan-US alliance."

Japanese news agency Kyodo News reported on Monday that the "Japanese and US personnel checked coordination between their systems, with multiple launch rocket systems from the Japanese side firing a total of 24 rockets at a target about 13 kilometers (8 miles) away."

Earlier, US President Joe Biden pledged during a phone call with his Ukrainian counterpart, Volodymyr Zelensky, to provide Ukraine with a fresh $625 million security package, which includes arms and equipment, such as HIMARS, artillery systems, ammunition, and armored vehicles, according to a White House said in a press release.

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US weapon supplies 'uncomfortably low' due to Ukraine aid: WSJ

The Wall Street Journal reported back in August that 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, according to the Wall Street Journal (WSJ). 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.

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.

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

In another report 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 for the economic hardship the United States is facing.

Earlier 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.