It is estimated that there are currently around 13,500 nuclear warheads around the globe, and despite being distributed among nine nuclear powers, more than 90% of them are part of either the Russian or American arsenals. The United States has around 5,800 nuclear warheads while the Russian arsenal stands around 6,375. However, total spending in these nuclear programs is not distributed quite in the same way.
In 2019, the total global spending stood at $72.9 billion, of which the United States spent $35.4 billion. This is almost half of the total, while the Russian counterparts spent only $8.5 billion. Why is this gap in the budget so wide if both arsenals have roughly the same amount of warheads?
The answer lays in modernization. Most of the Russian budget is destined towards the maintenance of these warheads. Also, while the Russians also destine some of it towards operations to keep these warheads deployed, Russia does not currently spend a significant amount of resources towards modernization. This is understandable since these $8.5 billion already represent 13% of the defense spending.
On the other hand, the United States spends a considerable amount of money on the modernization of the nuclear triad. Added additionally to the cost of maintaining these warheads, the United States started a journey towards modernization. It is estimated that this project is to be finished around 2046 and that the total expenses destined towards this endeavor represent a total of $1.2 trillion dollars starting in 2017. The most relevant expenses included in this projection are the Columbia class submarines, the new B-21 bombers, a new ICBM and ALCM fleet, as well as funds destined to the Department of Defense and the National Nuclear Security Administration. Lastly, despite these plans, the United States has managed to limit spending towards nuclear weapons to 5% of the defense budget, a number way under the 13% presented by Russia. Continuous spending of $35.4 billion until 2046, the date used in the projection, yields total spending over $1 trillion, demonstrating that in order to achieve this new nuclear arsenal, the United States is likely to stay under 13% of its defense budget.