In recent weeks, concerns over the modernization of the US nuclear arsenal have come to the forefront as geopolitical tensions with Russia and China continue to escalate. With increasing worries of a conflict involving the use of nuclear weapons, experts and organizations are questioning the logic behind the $1.5tn effort to upgrade the US nuclear arsenal.

The US army corps of engineers has initiated the removal of radioactive remnants from Robert Oppenheimer's Manhattan Project on Staten Island, while work at the Los Alamos national laboratory in New Mexico is being intensified to produce plutonium "pits" - crucial components of warheads in the US nuclear arsenal.

The need to replace aging intercontinental ballistic missiles with a successor, the Sentinel, has prompted concerns about placing new missiles with potentially more warheads in the heartlands of the United States. A recent report in Scientific American questioned the decision, asking why the country would risk placing a nuclear target in the breadbasket of the nation.

One of the pressing issues surrounding the modernization effort is the production of the cores of nuclear warheads, particularly the plutonium pits. The US has not been able to produce pits in the quantities required to update its stockpile of warheads since 1989. The degradation of plutonium over time has raised questions about the lifespan of the pits, with estimates varying on when they become too soft to be usable. Experts suggest that most pits are already over 40 years old, but some studies indicate they could last up to 80 years.

To address this challenge, the National Nuclear Security Administration (NNSA) formulated a plan in 2018 to increase pit production by maximizing production lines at Los Alamos and converting a plant near the Savannah River in South Carolina. However, the project was ultimately unsuccessful and canceled in 2020, leaving no pit-production expertise at the South Carolina facility.

The lack of a comprehensive schedule and rising cost estimates have further complicated the modernization plans. The current cost for producing fewer pits has already risen from $3.6bn to over $11bn. The Government Accounting Office (GAO) warned in January that the NNSA's plutonium modernization program had not developed a cost estimate meeting GAO best practices.

The concerns regarding US nuclear weapons have resurfaced alongside increased tensions with Russia and China. Russian posturing over the use of battlefield nuclear weapons in Ukraine, as well as the overflight of a Chinese spy balloon near critical areas for US nuclear deterrence, have put nuclear weapons back into the public consciousness. UN Secretary-General António Guterres has warned of a "worrisome new arms race" and the potential increase in the number of nuclear weapons.

While fears over nuclear conflict had diminished compared to concerns over climate change, experts now suggest that the probability of a nuclear war should not be disregarded. Frank N von Hippel, a US physicist and co-director of the program on science and global security at Princeton University, highlights the uncertain timeframe for the degradation of plutonium pits, emphasizing the need for a thorough understanding before restarting production.

As the US spends approximately 5% of its military budget on nuclear weapons, the Biden administration has shown support for refurbishing the aging stockpile. The stakes are high as nuclear risks continue to rise amidst a changing geopolitical landscape.