Amid growing concerns of depleting stockpiles, the US Army announced on Monday it awarded more than $520 million in contracts to Lockheed Martin to refill stocks of guided multiple launch rocket systems (GMLRS) sent to Ukraine.

"The US Army awarded multiple contract options worth $520.814 million on Oct. 21 and Nov. 2, 2022, to Lockheed Martin for Guided Multiple Launch Rocket Systems in order to replenish GMLRS provided from DoD inventory to Ukraine," the US Army said in a press release.

On September 7, US Army Chief of Staff Gen. James McConville said the US needs to replenish and upgrade its stocks of military equipment, just a few days after an article by WSJ reported, citing a US defense official, that the quantity of 155mm combat ammunition in US military storage has dropped to "uncomfortably low" levels. 

US media reported in late August that the Pentagon is concerned US weapons shipments to Ukraine are depleting the nation’s own stockpiles, particularly ammunition supplies.

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). On its part, the US Department of Defense has been hesitant to replenish its arsenal, raising fears among US officials that the shortfall might undermine military readiness.

Read more: US State Dept. approves potential $495Mln sale of HIMARS to Lithuania

On September 15, the US DoD announced that the United States has given the Raytheon-Lockheed Martin Javelin Joint Venture a $311 million contract for 1,800 Javelin missiles to replenish stocks deployed to Ukraine.

On the same day, it was reported that NATO is collaborating with the defense industry to restock its arsenal, which has been depleted as a result of the supply of armaments to Ukraine by the bloc.

On September 21, a senior US Air Force official revealed that the US air service branch and Space Force are using some of the oldest equipment in their history.

"Our air and space forces of today are operating some of the oldest equipment in our history," he said.

On October 24, a former Pentagon official told sources that the $17.6 billion worth of military equipment provided to Ukraine is pressuring the US defense industry's capacity to replenish stockpiles. 

"I was talking to somebody that works at a company that produces some of those munitions that we're depleting because we're giving a lot of it to Ukraine right now, and I said, 'How long is it going to take you to get your line up and running,' they said it's gonna be about two years," the official, Wesley Hallman, said.

On November 10, an article by the National Interest magazine said the US military is facing a "sharp reduction in its arsenal" due to military supplies to Ukraine.

"The Biden administration’s efforts to assist Ukraine in its war with Russia shine a light on two serious national security problems," the article said. The first problem is the Department of Defense’s inadequate stockpiles of munitions. The second problem is about how the depletion of US stockpiles is affecting the US' capabilities to be ready in the face of potential contingencies. The article noted the difficulties facing the defense industrial base to respond to quickly increase the production of critical items.

Read more: Zelensky visits Kherson, Kremlin responds