The House Armed Services Committee on Wednesday began to ink the contours of the 2021 nuclear-weapons budget fight to come, when the committee chair wondered in a hearing why the White House wants to give the Department of Energy a $2.5 billion raise over 2020 with the civilian nuclear weapons agency sitting on $8 billion in unspent appropriations.

The White House’s controversial plan to to plus up the DoE’s National Nuclear Security Administration (NNSA) to $20 billion in 2021 would mean the Navy can fund only a single Virginia-class attack submarine in the fiscal year that begins Oct. 1, rather than the pair the department wanted.

On Wednesday, the House Armed Services Committee’s Democratic chair wondered whether the Navy even had to make that sacrifice, with the NNSA sitting on a pile of cash.

“If we got $8 billion hanging out in there that we haven’t spent as planned, I question the wisdom of grabbing $2.5 billion to add to that,” Rep. Adam Smith (D-Wash.), chair of the House Armed Services Committee, said in a hearing devoted to the Department of Defense’s 2021 budget request of about $705 billion.

Nobody at the hearing said exactly how the NNSA accrued this unspent $8 billion, and a spokesperson for the agency did not immediately reply to a request for comment Wednesday evening.

The ranking Armed Services Republican warned Wednesday that the NNSA might already have plans for the $8 billion in uncosted balances that Smith, only one hearing into the 2021 budget cycle, is already eyeing.

“I think it’s up to us to dig deeper into exactly where those [unspent NNSA] funds come from,” Rep. Mac Thornberry (R-Texas) said during the hearing. “Are they intended for a particular purpose? A construction project that’s delayed? A weapon refurbishment for example, that’s been delayed, and I know we’ve got some of that.”

At the hearing, the Secretary of Defense and the chair of the Joint Chiefs of Staff — the nation’s highest-ranking, uniformed military officer — both were cool about the plan to clip a Virginia sub from the budget.

“[M]y gut tells me we need more attack submarines than planned,” Secretary of Defense Mark Esper testified.

Asked by Rep. Susan Davis (D-Calif.) whether he thought it was “good prioritization” to cut a Virginia-class submarine to lift the NNSA budget, Army Gen. Mark Milley, chair of the Joint Chiefs of Staff, said, “no, it is not, ma’am.”

Yet both Pentagon leaders hedged their remarks.

Esper floated a legislative solution that would let the Navy make up for some of the funds the White House proposed diverting to the NNSA in 2021: allow the service to sweep up unspent funds at the end of the a fiscal year and transfer them into the Navy Shipbuilding and Conversion account.

“We think that could generate at least $1 billion a year or so that we could plunge back into ship building,” Esper said. “[T]hat’s something that other departments of the federal government already have available to them,” Esper added.

The NNSA is one agency that — barring congressional direction to the contrary — already enjoys the ability to hold on to its appropriations year-to-year, rather than sending unspent funds back to the treasury each Oct. 1.

Milley, despite his preference for a Virginia-class submarine this year, said he “supported the full funding of the nuclear enterprise.”

The White House has requested a $19.8 billion budget for the NNSA in fiscal year 2021, which would be 20% higher than the 2020 appropriation of $16.7 billion, and billions of dollars more than the agency forecast last year that it would need in 2021.

The NNSA is retooling the way it does its accounting in fiscal year 2021 and still had not released its detailed 2021 budget justification at deadline Wednesday. However, NNSA Weapons Activities programs, the account that funds nuclear weapons refurbishments and the rebuilding of the nuclear weapons production complex, is in line for a 25% raise in 2021 to more than $15.5 billion. That accounts for almost the entire budget request NNSA seeks.

Meanwhile, Esper danced around questions about the proposed W93 submarine-launched ballistic missile at Wednesday’s hearing.

Rep. Salud Carbajal (D-Calif.) asked Esper why the NNSA required $53 million for the proposed weapon in 2021, which is two years sooner than the semi-autonomous DoE weapon steward thought it would need the funding. Why, Carbajal asked, is the government rushing to develop a successor to the W76-1, W76-2 and W88 Alt-370 warheads when each of those Trident II D5 tips has either just finished a modernization program, or will soon.

Esper deferred to the NNSA, and Carbajal did not press him, or follow up on the questions.

Secretary of Energy Dan Brouillette was scheduled to testify Thursday on the DoE’s 2021 budget request before the House Appropriations energy and water development subcommittee. Lisa Gordon-Hagerty, administrator of the NNSA, is expected to testify on the NNSA budget request March 3 before the House Armed Services strategic forces subcommittee.