The LGM-35A Sentinel intercontinental ballistic missile (ICBM) program faces significant overruns and delays, casting an unwelcome spotlight on America’s aging US nuclear arsenal and contrasting sharply with the rapid modernization efforts of near-peer adversaries China and Russia.
The National Interest (TNI) reported this month that the LGM-35A Sentinel ICBM, developed in tandem by the US Air Force and defense contractor Northrop Grumman, is expected to cost 37% more than originally budgeted and take at least two years longer to reach initial operational capability than previously projected.
TNI notes that the Sentinel’s delay will require the US Air Force to extend the life of some of its Minuteman ICBMs, which were activated in the 1970s and comprise one of the three major components of the US nuclear triad.
Replacement of the ground-based US nuclear arsenal anchored by the Minuteman III has officially exceeded its US$95.8 billion budget, due to the Covid-19 pandemic and inflation. TNI notes that the cost overrun owes to the modernization of 450 missile silos and their command infrastructure, which includes 12,070 kilometers of new cables.
The US Department of Defense (DOD) has no choice but to push the program through, with costs potentially rising to over $125 billion. TNI reports the US Air Force expects a new cost and schedule for the LGM-35A Sentinel by summer 2024 if the program is allowed to continue.
The LGM-35A Sentinel is envisioned to replace LGM-30G Minuteman IIIs by 2029 and remain in service until the 2070s. The system features a modular design and open architecture, allowing for easy replacement of aging components and cost-effective maintenance.
Modularity also reduces maintenance costs by enabling the replacement of missile subsystems without redesigning the entire weapons system. The LGM-35A Sentinel also has improved security features, with lighter composite materials for increased throw weight and capacity.
Delays in LGM-35A Sentinel production could mean that the US has to rely on increasingly obsolete nuclear weapons for strategic deterrence, in contrast to its near-peer adversaries China and Russia, both of which have continuously modernized their nuclear arsenals.
More significantly, the US may be having greater problems in producing nuclear warheads than upgrading their delivery systems.
In a Heritage Foundation report this month, Robert Peters and Maiya Clark point out that while the US has been building new nuclear delivery systems since 2010, the problem is in the nuclear warheads themselves. The writers note that the US’ latest nuclear warhead, the W-88, entered service in 1989 while other types, such as the B-61 nuclear gravity bomb, came off the assembly line in 1963.
Peters and Clark note that the US cannot use plutonium from decommissioned warheads in new ones, saying that even if plutonium has a 24,000-year half-life, microscopic changes in the warhead plutonium can affect the storage safety and explosive yield of nuclear weapons.
They add that existing US plutonium nuclear pits, spherical shells that represent the core of an implosion nuclear weapon, were designed for older weapons and may not give the desired results when used in newer weapons.
While the US must produce 80 plutonium pits by 2026 to modernize its nuclear arsenal on a one-to-one basis, current US plutonium pit production capacity means that it won’t have 80 pits annually until 2030 and possibly not until 2040.
Peters and Clark attribute this shortfall to a culture of complacency that emerged after the Cold War, a lack of skilled nuclear expert workers, flagging industrial infrastructure and restrictive environmental regulations surrounding plutonium processing.
In a December 2023 Scientific American article, Sarah Scoles notes that the US last produced plutonium pits in the late 1980s. Given that shortfall, Scoles mentions that the US National Nuclear Security Administration plans to build 50 new pits yearly at the Savannah River Site in South Carolina and 30 at Los Alamos National Laboratory in New Mexico.
She notes that the first new pits would be for a new warhead, the W87-1, which would arm the LGM-35A Sentinel. Facilities would then produce more pits for newer nuclear weapons.
Scoles mentions that since plutonium was first made 80 years ago, nobody knows what would happen to the element past that point.
She says that JASON, a clandestine group of scientists, advised the US government in 2007 that US plutonium pits would last decades longer, implying no new need to manufacture new pits.
However, JASON reversed its position in 2019, urging the US government to restart the production of plutonium pits parallel to a focused program to understand plutonium aging.
Scoles says that the US National Nuclear Security Administration’s studies predicted that plutonium pits could last 150 years, but acknowledges that their degradation could result in surprise defects.
However, Scoles mentions that restarting US pit production is proving challenging, pointing out that Los Alamos’ efforts are a year behind schedule and Savannah River’s by five years.
In contrast to the US, China is going full speed ahead with fissile material production, in line with enlarging and modernizing its nuclear arsenal.
In a Federation of American Scientists report this month, Hans Kristensen and other writers note that while China stopped production of weapons-grade plutonium in the 1980s, it has combined its civilian technology and defense industrial bases and will likely source significant stocks of weapons-grade plutonium from civilian reactors.
The writers say those include two CFR-600 fast breeder reactors under construction at Xiapu in Fujian province.
Kristensen and others note that the first reactor may have begun operation in October 2023. However, they say it is not generating electricity and is not connected to the power grid, while the second reactor is scheduled to come online by 2026.
They mention that once both reactors come online, they could enable China to produce 330 kilograms of plutonium annually, which would be consistent with US estimates that China will have more than 1,000 additional nuclear warheads by 2035 on top of its current estimated arsenal of 500.