This article is part of a series on Upgrading America’s Nuclear Triad.
In the post-WWII era the United States Navy was eager to demonstrate its ongoing relevance. With nuclear weapons available, the Navy seemed obsolete. The Korean War proved that the Navy would continue to be essential to conventional conflicts. Nevertheless, the Navy began to compete with the Air Force for a critical role in the United States’ strategic forces. The Japanese I400, which had been captured and studied by the US Navy, had demonstrated the submarine’s capability as a means of deploying aircraft. It did not take long for naval designers to tie the long-range missile to the submarine as a weapons system combination with infinite potential. Nuclear power would only further this capability by providing a submarine capable of long extended voyages beneath the sea without the need to surface and recharge batteries. The submarines would, however, have to surface and expose themselves to attack in order to launch these early missiles.
In the late ’50s the Navy successfully tested a means of launching missiles vertically from 150 ft beneath the sea. Safe beneath the waves, a submarine could launch its compliment of missiles and disappear into the depths. The ever present fear that a submarine might be hiding anywhere in the depths would come to serve as America’s primary strategic deterrent. The Soviet Union competed with this capability, but not nearly as effectively. With few bases from which to launch, Soviet subs were constantly tailed by US attack submarines. US ballistic missile subs (SSBNs), by contrast, were able to navigate the seas relatively free of harassing Soviet attack subs. Capable of deploying a massive barrage of missiles with MIRVs that can deliver warheads to multiple targets, from virtually any place in the vast oceans; the submarine is by far the most formidable strategic weapon.
The early Polaris and Poseidon missiles had a limited range and required the submarines to travel closer to their targets in the USSR. The Trident I C4 and, now, the Trident II D5 missiles offer a vastly increased range and can be launched toward virtually any target from almost anywhere in the world’s oceans. In the 1980s the Navy began deploying the Ohio class ballistic submarine: each carries 24 missiles, is over 500 ft long, and can operate for 70-80 days at sea without surfacing. Originally designed for the Trident I missile, these were upgraded with the Trident IIs as the Cold War drew to a close. The first Ohio class submarine entered service in 1981 and the last in 1997 for a total of 18 boats. The first four submarines were taken out of strategic service in 2001 and have been refitted to carry conventional guided cruise missiles, as SSGNs. The 14 boats that remain continue to conduct about 25-30 deterrent patrols per year with their Trident II missiles. Again, these boats and their missiles are aging.
Replacing the Ohio Class
A programme to develop a replacement submarine for the Ohio class has been authorized. Likewise, the United Kingdom is looking to replace its four Vanguard class Trident Submarines. The US and UK could collaborate on a joint project and develop a single class to satisfy the needs of both. Only 12 submarines are planned for the Ohio replacement programme, as this is thought to be the minimum number to maintain effective deterrent patrols. The high cost of each submarine means that the smallest number are to be constructed. The UK plans to replace all four of their boats hull for hull. The Ohio class is aging as are the Trident II missiles.
These new boats are being designed to carry 16 missiles down from the 24 of the Ohio class. The Ohio replacement is also being designed with electromagnetic propulsion. An electric motor will drive the propeller which reduces the nuclear power plant to the generation of electricity. This system will replace reduction gears necessary to turbine driven submarines, which generate some noise and vibration. The Navy might also explore the integration of Air Independent Propulsion (AIP) to reduce noise and vibration. This hydrogen fuel cell technology has served Germany and Israel well in the Type 212/Dolphin class submarine, providing power for electric motors without the need for pumps and turbines.
Currently, only 12 Ohio replacement submarines are planned to be built, but it would be best to replace all 14 current strategic deterrence submarines with an equal number. It might also be prudent to build two additional hulls which could serve in a conventional capacity as guided missile submarines (SSGNs), these could later be retrofitted into a strategic deterrence role should circumstances require an increase in deterrent patrols, or as older boats need to be decommissioned.
Naturally, the lessons learned from the Virginia class will be incorporated. The Virginia class are built with a modular design that allows completed internal modules to be inserted into place within the hull. Later, the hull can be opened and modules replaced with upgraded modules. Many cost saving methods have also be incorporated that will be employed in the Ohio replacement class.
A New SLBM?
Since the Ohio replacement class is intended to hold only 16 missiles to the Ohio class’ 24, it stands to reason that a new missile might be developed to increase America’s SLBM capability. A new missile system can also be designed so as to increase longevity and reduce long-term operational costs. Replacing the aging Trident II D5 missile with a Trident III E6 missile of comparable range and a larger payload of warheads, would be a significant improvement to the most effective and formidable means of maintaining strategic nuclear deterrence.
Click here to return to the main article: Upgrading America’s Nuclear Triad.