Does Washington have the stomach to pay for its nukes?

“It’s our most important mission but sometimes a forgotten one,” he said.

As the country prepares to recognize the moment 70 years ago that the U.S. dropped its first nuclear weapon, it faces what Rep. Vicky Hartzler, R-Mo., called a “critical inflection point for our nuclear forces.”

“As the age of U.S. nuclear weapons increases and some of our bombers, submarines and intercontinental missiles become older than the personnel who maintain and operate them, potential adversaries are fielding newer and more advanced nuclear arms,” the committee member said during a late June hearing examining planned fixes for the air, land and sea legs of the country’s nuclear program. “Many prospective foes are also making nuclear weapons more, not less, central to their national strategies.”

While there is agreement on Capitol Hill that maintaining and upgrading the U.S. arsenal, the hang up will be how to pay for it.

Despite past concerns that upgrading the arsenal is “unaffordable,” consensus is growing that the notion is not the case. But it will force tough choices, lawmakers and top Defense Department officials said.

“As it stands, any remaining margin we have for investing in our nuclear deterrent has been steadily whittled away as we’ve pushed investments further and further into the future,” Adm. James “Sandy” Winnefeld, then-vice chairman of the Joint Chiefs, told the House Armed Services Committee in June. “The fact is there’s no slack left in the system. We will need stable, long-term funding to recapitalize this most important element of what we do. We can no longer adjust priorities inside the nuclear portfolio to make things work, to string it along.

“That implies that absent some other form of relief, because this is our highest security, we’re going to have to reach into the other things we do to protect other national security interests. That’s going to make many people, both inside and outside DoD, unhappy,” he said.

So why spend the money? At that same hearing, Deputy Defense Secretary Bob Work sketched out the threats.

“We face the hard reality that Russia and China are rapidly modernizing their already capable nuclear arsenals, and North Korea continues to develop nuclear weapons and the means to deliver them against the continental United States,” Work said. “So a strong nuclear deterrent force will remain critical to our national security for the foreseeable future.”

Russia has been accused of violating the Intermediate Nuclear Forces Treaty of 1987, which requires Moscow and the U.S. to destroy ground-launched ballistic and cruise missiles in the 500-5,500 kilometer range.

“Now, let me just say this about Russian military doctrine that sometimes is described as ‘escalate to deescalate,'” Work said. “Anyone who thinks that they can control escalation through the use of nuclear weapons is literally playing with fire. Escalation is escalation, and nuclear use would be the ultimate escalation.”

China, meanwhile, is adding warheads to its intercontinental ballistic missiles, expanding its mobile ICBM force and developing a sea-based strike element, Work said. “However, we assess that this modernization program is designed to ensure they have a second strike capability, and not to seek a quantitative nuclear parity with the United States or Russia.”

North Korea, in a general sense, is expanding its nuclear weapons program, but the U.S. expects to stay ahead of Pyongyang’s projected capabilities, Work said.

The cost of keeping up with the threat, in the meantime, is the subject of debate. Work said the Defense Department projects an average cost of $18 billion per year from 2021-35 in fiscal 2016 dollars to transition aging systems to newer ones.

“Without additional funding dedicated to strategic force modernization, sustaining this level of spending will require very, very hard choices and will impact the other parts of the defense portfolio, particularly our conventional mission capability,” Work said.

But a recent Center for Strategic and Budgetary Assessments report estimates that costs over the next 25 years will peak in fiscal 2027, then begin to decline through to 2039. The numbers, as a percentage of total defense spending, never go above 5 percent each year.

“In comparison, the U.S. military spends more than twice as much on healthcare each year — roughly 10 percent of the budget — than it does on nuclear forces,” the report’s authors, Todd Harrison and Evan Braden Montgomery, wrote.

“Our analysis concludes that U.S. nuclear forces are affordable because their projected costs account for a small percentage of the overall defense budget [3-5 percent],” they wrote, “even when supporting systems and infrastructure are included.

“Thus, the issue is not affordability — rather, it is a matter of prioritization.”

House Armed Services Chairman Rep. Mac Thornberry, R-Texas, asked Work if he thought those numbers rang true. Work said the study is “credible,” but thinks the number is closer to 7 percent of defense spending. But the number could go higher due to funding shortfalls brought about by sequester-related spending cuts since 2011.

Thornberry said the opposition will come from those who don’t view the problem as a problem at all.

“Part of the reaction one gets is, OK, we’ve been dealing with this for 70 years. It’s gone along pretty well, nothing has really changed,” he said. “There’s really no need to spend all this money because we’ve been making it OK. And besides, we’ve got enough weapons to destroy the world several times over. So, really, you’re just asking us to waste money to put it into the warheads or delivery systems.”

Work responded: “Anybody who looks at the way that the international environment is moving, especially the way that Russia has been describing its nuclear deterrent posture, has to say, ‘Nuclear weapons remain the most important mission we have. This is absolutely critical.'”