A top U.S. Navy official is defending the service’s plans to replace its Ohio-class ballistic missile submarine fleet, saying the Navy has the right design and boat numbers to execute the mission for decades to come.

“We conducted a detailed analysis of many force structure options,” says Rear Adm. Barry Bruner, Navy undersea warfare director, in a recent blog. “A force of 12 Ohio Replacement nuclear-powered ballistic missile submarines (SSBN) with 16 missile tubes satisfies national strategic deterrent requirements at the most affordable cost. Twelve Ohio Replacement SSBNs meet at-sea strategic patrol requirements and sustain this requirement while some of the SSBNs are unavailable due to planned maintenance.”

Bruner says, “Reduced-force options [that] we considered failed to meet the current at-sea and nuclear employment requirements, increased risk for force survivability, and limited the flexibility in response to an uncertain strategic future. A 12-ship, 16-missile-tube SSBN force has sufficient, not excessive, flexibility and capacity.”

He acknowledges that because ship construction of the Ohio Replacement shifted to 2021 from 2019, there will be fewer than 12 SSBNs from 2029 to 2042 as the Ohio-class retires and Ohio replacement ships join the fleet.

Addressing recent critics of the shortfalls, he says, “During this time frame no major SSBN overhauls are planned, and a force of 10 SSBNs will support current at-sea presence requirements.”

However, he says, “This provides a low margin to compensate for unforeseen issues that may result in reduced SSBN availability. The reduced SSBN availability during this time frame reinforces the importance of remaining on schedule with the Ohio Replacement program to meet future strategic commitments. As the Ohio Replacement ships begin their mid-life overhauls in 2049, 12 SSBNs will be required to offset ships conducting planned maintenance.”

He also says the Navy and Pentagon are keeping a lid on proposed costs. “The Department of Defense set an aggressive cost goal of $4.9 billion per hull (calendar year 2010) as an average cost for hulls 2-12. To date, the Navy has reduced costs by reducing specifications to the minimum necessary to meet national strategic deterrent requirements, implementing modular construction design, reusing the Trident II D5 Strategic Weapons System, and reusing Virginia- and Ohio-class components where feasible. The Virginia-class construction program, through aggressive management and collaboration between government and industry, has developed into a model ship building program, continually coming in under budget and ahead of schedule. Ohio Replacement design and construction will build on this success.”