The United States has not published figures about its Javelin inventory, so this must be deduced.
According to the Army budget books, total production has been 37,739 since production began in 1994. Every year, U.S. forces use some missiles for training and testing. Thus, there may be 20,000 to 25,000 remaining in the stockpiles. These 7,000 systems represent about one-third of the U.S. total inventory.
That fraction doesn't sound like much; after all, two-thirds of the inventory remains. However, military planners are likely getting nervous. The United States maintains stocks for a variety of possible global conflicts that may occur against North Korea, Iran, or Russia itself. At some point, those stocks will get low enough that military planners will question whether the war plans can be executed. The United States is likely approaching that point.
The obvious answer is to build more missiles (and launch units, the control box that goes on the missile). The United States has been buying Javelins at the rate of about 1,000 a year.
The maximum production rate is 6,480 a year, though it would likely take a year or more to reach that level. The delivery time is 32 months; that is, once an order is placed, it will take 32 months before a missile is delivered. This means that it will take about three or four years to replace the missiles that have been delivered so far. If the United States delivers more missiles to Ukraine, this time to replace extends.
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One system for which inventories and replenishment rates are limited is the Stinger anti-aircraft missile.
According to the White House fact sheet, the United States has provided 2,000 Stingers to the Ukrainians. The United States has not purchased any since 2003. At that time, the total production was stated as 11,600 missiles (
from the FY 2000 budget documents). With testing and training losses of 1 percent a year, the remaining inventory would be about 8,000. So, the United States has sent about a quarter of its inventory to Ukraine.
In 2003, the last time the United States procured Stingers, production rates were stated as 275 with standard shifts (called "1-8-5") and 720 at maximum production rate. Production lead time was 24 months. That means it will take at least five years to replace the inventory drawdown (two years for lead time and three years for production).