As the House and Senate gear up for votes in the coming days to fund the Defense Department, lawmakers are set to support a bow wave of costly nuclear weapons programs increasingly at odds with the needs of U.S. troops and the future threats that dominate their agenda.

Notably for a president who famously championed nuclear disarmament, the Obama administration’s plans to beef up the nation’s nuclear arsenal exceed even that of President Reagan’s. But the cost does not come without compromise. Lawmakers must consider the very real choice between additional nuclear weapons spending and conventional weapons needs. Because the Pentagon cannot plan for every contingency, it must plan for the most conceivable future. In this case, that might mean a step back from nuclear weapons toward greater focus on those weapons we might actually use.

Laicie Heeley

Plans to modernize all three legs of the nuclear triad are slated to cost a total of $348 billion over the coming decade, according to estimates from the Congressional Budget Office (CBO), and as much as $1 trillion in the years beyond. But this cost does not come without tradeoffs. Systems we really need, like Army combat helicopters, theater missile defenses and advanced drone development don’t enough money already and it’s going to get worse.

Post-Cold War generations have grown up with an immense sense of understanding the risk of nuclear war. They understand not only that hiding under a school desk won’t save a classroom of children from a nuclear blast, but also that the devastation caused and havoc wreaked by the use of these weapons is so great that the likelihood of their use, particularly by the United States, isn’t so likely. The consequences of a nuclear blast aren’t just the stuff of scary movies. We all know how the movie ends.

What is not clear is the next stage of warfare, or terrorism, or where U.S. conventional forces might be forced into battle next. Cyber warfare, biological warfare and climate change, all have the ability to inflict widespread devastation in a way that has yet to play out. And in what some have called a post-post-Cold War world, the boundaries of conventional warfare have become less and less clear.

While the potential devastation is horrible, the rules of nuclear deterrence are less opaque. The U.S. maintains a large nuclear arsenal to deter those rational actors which might consider an attack. This works because the doctrine of mutually assured destruction governs that which can be identified, including the culprits of such an attack. While some might argue for the extension of this theory into cyberspace, the truth is that in this new era of war, the culprit is not always so easy to identify. The world is more complicated, and the U.S. must develop new means with which to counter these threats.

It follows logically that investment in nuclear weapons, given their primary value as a deterrent, should fall. But so far this has not been the case. Rather, the U.S.’ current nuclear modernization plans are vast, sweeping, and threaten to outsize the conventional weapons U.S. troops need to get the job done. This was one of the central findings released in a Stimson report today.

Ohio-class ballistic missile submarine USS Tennessee

The cost of the Navy’s new nuclear submarine (Ohio Replacement Program), in particular, has the ability to overwhelm its shipbuilding budget to the detriment of other options. Alternatives such as the sea-based deterrence fund, which would clear up the Navy’s budget by moving funding to the defense-wide account, are not just irresponsible, but incapable of execution without significant tradeoffs under current law. While Congress is eventually expected to strike a deal that raises budget caps put in place by the 2011 Budget Control Act, it is unlikely to get the large increase to Pentagon funding it seeks. And even under a deal, slightly higher caps will remain in place for the years to come, making it harder for the Navy to execute such a workaround.

Further plans to develop a new air-launched, nuclear-capable cruise missile (ALCM) drew fire at a hearing of the Senate Appropriations defense subcommittee last week, when Democrat Sen. Dianne Feinstein noted that the missile represented only half the true cost: “I question why we need this cruise missile that can deliver nuclear warheads from great distances in addition to the numerous gravity bombs, submarine-launch ballistic missiles and intercontinental ballistic missiles we’ve armed ourselves with,” Feinstein said.

Laicie Heeley is a fellow in the budgeting for foreign affairs and defense program at the Stimson Center.