NATO (North Atlantic Treaty Organization) has said it is struggling with ammunition shortages caused by the war in Ukraine with Russia. The dwindling supply of artillery ammunition has served as a wake-up call to NATO, the United States and Western officials told CNN.

The alliance did not adequately prepare for the possibility of a protracted land war in Europe following decades of relative peace, CNN reported. U.S. officials emphasized to CNN that there is a set level of munitions in U.S. stockpiles around the world, essentially an emergency reserve, that the military is not willing to part ways with. The levels of those stockpiles are classified.

The United Kingdom’s Secretary of Defense Ben Wallace told CNN last week that while NATO was poised early on for a “night one, day one” offensive, “no one had really asked themselves the question, well, what if ‘day one, night one’ becomes ‘week two, week three, week four?’ How much of our exquisite capabilities have we actually got in stock? And I think that’s been the broader question.”

But officials say the US has been nearing that red line as it has continued to supply Ukraine with 155mm ammunition, the NATO standard used for artillery rounds. The US began ramping up ammunition production last year when it became clear that the war would drag on far longer than anticipated. But the ammunition will still take “years” to mass produce to acceptable levels, National Security adviser Jake Sullivan told CNN Sunday. –CNN

A German government source told CNN that Berlin is going to attempt to close the “existing gaps” in ammunition stocks and to increase ammunition reserves. Germany also noted that the munitions for the Swiss-made Gepard tank, which has been provided to Ukraine, are now being produced in Germany. Ammunition from that new production line is expected to be delivered this summer, which would allow Germany to ship its own rounds since Switzerland remains unwilling to send its supply, according to CNN’s source.