The head of U.S. Strategic Command warned early this week of the "precipitous risk" in the next decade as the Ohio-class ballistic missile submarines reach retirement and are no longer able to go underwater.

"Each submarine is built to go down, under pressure, a certain number of times. Once you reach the end of life, it can't go down anymore," Gen. John Hyten said Tuesday before the Senate Armed Services Committee. "A submarine at the top of the water is not an effective deterrent."

Hyten said he could not publicly specify when the Ohio-class boats would reach that point but said it will start toward the end of the next decade. Starting in 2027, the Ohio-class boats will be retired at a rate of one per year. It's not possible to further extend their lifespan, according to Hyten.

The remarks were part of a larger argument he made about the need to modernize the U.S.'s nuclear arsenal and to keep the $100 billion program to replace the Ohio-class boats on schedule.

The U.S. will need to spend 6 percent of its defense budget to modernize its nuclear weapons, as opposed to the 2.5 percent it spends now, according to Hyten. The defense budget, as a whole, makes up more than 50 percent of U.S. discretionary spending.

At an annual meeting of the Military Reporters and Editors Association in Arlington, Va., last week, Hyten indicated that he'd like to see more discussion in the news media about the role of nuclear weapons. 

When the United Nations proposes banning nuclear weapons or someone makes an argument that the world should get to zero nuclear weapons, Hyten said "that's the only time you see it show up."

"And it's a blip on the screen for a few days and then it disappears again," he added.

The U.S. and Russia together possess more than 90 percent of the nuclear weapons in the world. Hyten said he supports the limits on strategic arms under the the New START treaty, the nuclear arms agreement between the two countries.

Hyten said he's frequently asked about whether he can imagine a world without nuclear weapons. He pointed to the six years before 1945, when between 60 million and 80 million people were killed during World War II.

"As horrible as the world is today, and it is nasty, it is not anywhere near like that," Hyten said.

The Ohio-class submarines will have the longest lifespan of any U.S. submarine, after the Navy decided in the late '90s to extend the boats' service life from 30 to 42 years for budgeting and scheduling reasons. To date, the longest-serving U.S. submarine is the USS Kamehameha, a ballistic-missile submarine, which was retired in 2002 after 36½ years in service.

Electric Boat is in the midst of detailed design work on the Columbia-class program, the development of 12 new ballistic-missile submarines to replace the current fleet of 14 Ohio-class boats. The first Columbia-class submarine isn't expected to go on patrol until 2030.

Under current plans, there are expected to be five Columbia boats and five Ohio boats in 2035. All 14 Ohio boats are expected to be retired by 2039, and all 12 Columbia boats are expected be in service by 2042, according to those plans. The Columbia-class boats will have 42-year nuclear reactors that won't require refueling.

U.S. Rep. Joe Courtney, D-2nd District, whose district includes EB, pointed to the $773.1 million that federal lawmakers secured this fiscal year for the Columbia-class program for design work and to purchase parts that take the longest to design and fabricate. The funding was included as an exception under the continuing resolution currently funding the government until April 28. Normally, under continuing resolutions, programs are funded at previous fiscal year levels, and no money is available for new programs.

Still, the Columbia program is on a "knife-edge timeline," Courtney said.

The head of the Navy, Adm. John Richardson, confirmed that Wednesday, saying, in response to a question from Courtney, that the $773.1 million is adequate for this year, but "stable, continuous funding" is needed to keep the program on track.

Richardson and the Army, Air Force and Marine Corps chiefs of staffs testified before the House Armed Services Committee about the negative impacts, such as curtailing combat operations and training, that continuing resolutions have on the Pentagon.

There's been talk of another continuing resolution to fund the government for the remainder of the 2017 fiscal year, which ends Oct. 1, 2017. If lawmakers don't find a way to fund the government, there will be another partial government shutdown.

j.bergman@theday.com