The U.S. will need to spend $348 billion over the next decade to maintain its nuclear arsenal, according to a new report from the Congressional Budget Office (CBO) released on Thursday.

The nonpartisan agency said that, while the estimated price tag is lower than a previous estimate of $355 billion in December 2013, the figure still amounts to 5percent-6 percent of the Obama administration’s national defense plan over the next 10 years

{mosads}The CBO attributes the lower tab to “budget-driven delays in several programs, including a three-year delay for the new cruise missile and its nuclear warhead.”

The Defense Department would be on the hook for $227 billion in costs, while the Energy Department would spend $121 billion, the agency estimates.

The updated estimate comes as the administration is set to unveil its fiscal 2016 budget on Feb. 2, and with sequester cuts set to resume, the timing could not be worse for the three legs of the U.S. nuclear “triad.”

The land-, sea- and air-based platforms and the atomic weapons they carry “are reaching the end of their service lifetimes,” the CBO warns.

“Over the next two decades, the Congress will need to make decisions about the extent to which essentially all of the U.S. nuclear delivery systems and weapons will be modernized or replaced with new systems.”

Kingston Reif, director for disarmament and threat reduction policy at the Arms Control Association, argues the cost of maintaining the arsenal could still top $1 trillion over the next 30 years.

He cites a report from the National Defense Panel’s 2014 Quadrennial Defense Review that found refurbishing all three legs of the triad would cost roughly that amount.

Last year, the think tank released a report that said the U.S. could save around $70 billion by adjusting plans for new ballistic submarines and bombers, delaying or nixing the purchase of new delivery systems and taking a new approach to rebuilding warheads.

“CBO’s reports on the projected costs of nuclear forces have brought a much-needed dose of fiscal perspective to the debate about the future of the U.S. nuclear arsenal,” Reif wrote.

“Whether one thinks the United States has too many or too few nuclear weapons, it is no longer possible to hide from their immense cost.”