Congress has been debating the possibility of fielding more nuclear weapons at sea. Both the House and Senate Armed Forces committees approved a provision to the 2023 National Defense Authorization Act that allows for additional funds for the Navy’s Sea-Launched Cruise Missile-­Nuclear program, better known as SLCM-N.

The SLCM-N is considered a “low yield” or “tactical” nuclear cruise missile. It would create a large, powerful blast compared with conventional missiles but generate an explosion considerably smaller than strategic nuclear weapons. It’s also a physically smaller munition than large nuclear ballistic missiles, allowing for easier storage and transportation.

The expansion of nuclear arms at sea could have implications for the Navy’s Hawaii-­based Pacific Fleet, and members of Hawaii’s congressional delegation sit on key committees that will determine the program’s future.

The U.S. military does not discuss the locations of nuclear armed weapons as a matter of policy, but the Pentagon considers the Pacific its top-priority theater of operations. Proponents of tactical nukes have cited China’s rapid military buildup and North Korea’s push to enhance its own missile technology as reasons to reconsider their use.

But both the military value as well as the potential risks of deploying tactical nuclear weapons are hotly debated within national-­security circles.

The SLCM-N program started under President Donald Trump, who called for more nuclear weapons in the American arsenal. The administration of President Joe Biden has attempted to shut down the project; it did not appear in the Navy’s 2023 military budget request. But Congress appears primed to pave the way for continued funding in spite of the White House’s objection.

Currently, the only U.S. nukes at sea are ballistic missiles launched from submarines. The Navy has 18 Ohio-class submarines, at least 14 of which are capable of launching Trident 2D5 nuclear-tipped ballistic missiles, each of which can hold up to 12 nuclear warheads.

But the new cruise missiles could potentially be stored and launched from the decks of surface ships as well as submarines.

Hawaii’s U.S. Rep. Kai Kahele and U.S. Sen. Mazie Hirono sit on their chamber’s respective Armed Serv­ices committees, which approved the continued funding and development of the missiles. The House passed its version of the annual National Defense Authorization Act in a floor vote in July. The version of the bill supported by the Senate Armed Services Committee contains the provision to continue funding the nukes, but the full Senate has yet come to a final agreement on the bill.

Hirono serves as chair of the SASC’s Seapower Subcommittee, making her the most senior lawmaker in overseeing Navy and Marine Corps policies and programs. Hirono declined to discuss the program, but an aide to the senator told the Honolulu Star-Advertiser that Hirono “has concerns about the use of tactical nuclear weapons and this funding.” Kahele’s office did not respond to requests for comment.

If the Senate version of the 2023 NDAA passes with approval for funding the SLCM-N, and Biden signs the bill into law, Senate and House Appropriations committees would then decide whether to actually continue funding the missiles. Hawaii’s U.S. Rep. Ed Case and U.S. Sen. Brian Schatz sit on their chamber’s respective Appropriations committees.

“Much of the debate on this question is classified,” Case said in an emailed statement to the Star-Advertiser. “In broad terms, the reality of the world we face, as opposed to the world we wish and hope we lived in, requires a diverse and unpredictable nuclear deterrence. How best to provide that is a matter of ongoing debate, including in Congress.”

Schatz’s office did not respond to requests for comment.

Ann Wright, a former Army officer and diplomat­-turned-activist based in Hawaii, said “U.S. nuclear submarines have so many nuclear weapons on their ballistic missiles that any more nuclear weapons is unnecessary.” She added, “The probability of accidental or mistaken discharge of nuclear weapons increases with each delivery system. As the world already could be destroyed with nuclear weapons from submarines, there is no reasonable rationale for nuclear weapons onboard surface ships.”

However, if the SLCM-N gets funded and makes its way onto surface vessels, it wouldn’t mark the first time the Navy has put tactical nuclear missiles on its ships. During the mid-1980s the Navy first deployed a nuclear-­armed version of the Tomahawk cruise missile called the TLAM-N aboard both surface ships and attack submarines.

But in the aftermath of the Cold War, President George H.W. Bush ordered the withdrawal of all tactical nuclear weapons aboard ships, submarines and naval aircraft. In 2010, President Barack Obama’s administration recommended in its Nuclear Posture Review that the missiles be retired entirely, arguing that “this system serves a redundant purpose in the U.S. nuclear stockpile.” The Navy disposed of the last of them in 2013.

Trump reversed course, calling for an expansion of the U.S. nuclear arsenal. In its 2018 Nuclear Posture Review, the Trump administration argued that sea-launched nuclear cruise missiles offer a “needed non-strategic regional presence” that would address “increasing need for flexible and low-yield options.”

The Biden administration’s latest Nuclear Posture Review is classified, but officials have said that it advocates cutting back much of Trump’s nuclear push.

According to an April Congressional Research Service report on the SLCM-N program, canceling it would save $2.1 billion over five years. “The Navy indicated that the program was ‘cost prohibitive and the acquisition schedule would have delivered capability late to need,’” the report said.

But the program retains several supporters. In April, Chairman of the Joint Chiefs of Staff Gen. Mark Milley, who was appointed by Trump, told members of the House Armed Services Committee his position on the weapon had not changed.

U.S. Strategic Command chief Adm. Charles Richard, who oversees the U.S. nuclear arsenal, also expressed support for the missiles during testimony before the Senate in May and reiterated his backing in a letter to lawmakers obtained by Defense News in June.

“I support reestablishing SLCM-N as necessary to enhance deterrence and assurance,” Richard said in the letter. “The current situation in Ukraine and China’s nuclear trajectory have further convinced me a deterrence and assurance gap exists.”

Hawaii is the home of U.S. Indo-Pacific Command and the Pacific Fleet, making it the nerve center for all military operations in the region. There has been ongoing debate on how to bolster missile defense of the islands, particularly after a false missile alert in 2018 rattled residents amid heated rhetoric between Trump and North Korean leader Kim Jong Un regarding missile policy.

Hawaii’s congressional delegation earlier this year withdrew support for the Homeland Defense Radar-­Hawaii, a controversial missile defense radar that the Pentagon spent years trying to defund under both Trump and Biden in hopes of investing in alternative systems as costs for the radar system piled up amid a struggle by planners to find a suitable on-island site and local pushback against the project.