A 22-year effort by Russia and the United States to permanently dispose of tons of plutonium that once fueled thousands of their nuclear weapons experienced a new setback this week, when Russian president Vladimir Putin abruptly announced his country’s withdrawal from an agreement spelling out how the work was to proceed.

Putin’s Oct. 3 announcement blamed the withdrawal in part on “unfriendly actions by the United States,” without specifying any. But the Obama administration hasn’t been bashful with the Russians, or with the public, about its own desire to step away from the agreement, because of the work’s high costs and technical challenges – not because of notably worsening relations.

The disposal method that Washington has been pursuing – and which is spelled out in the now-cancelled agreement – involves building a plant at the Savannah River Site nuclear installation in South Carolina to convert 34 tons of weapons-usable plutonium into fuel for commercial nuclear power plants while Russia converted a like amount. But a report by the Department of Energy and the U.S. Army Corps of Engineers last month said construction of the so-called Mixed Oxide (MOX) plant alone would not be complete until 2048 and that it would cost more than $17 billion, or roughly four times the cost promised in 1994, when the deal with Russia was initially struck.

In response to that new cost estimate, the Department of Energy – which manages this work – reiterated that it is eager to dispose of the plutonium instead in a burial pit, a less technically challenging alternative that it has said could bring a savings of up to $30 billion over the life of the project. The Obama administration actually approached Russian officials several years ago, seeking a potential modification to the agreement that would open a path to that approach.

The Russians’ announcement, as a result, is hardly a further blow to relations between the two countries. It means that Washington’s hands are arguably no longer tied by the agreement, allowing the next president to proceed with the burial option once the Energy Department solves a few remaining technical concerns (the optimum disposal site, the Waste Isolation Pilot Plant in New Mexico, has been closed since February 2014 due to a radiation leak caused by a drum of nuclear waste that ruptured underground).

At a State Department press briefing on Monday, Oct. 3. spokeswoman Elizabeth Trudeau called Putin’s decree, along with Russia’s refusal to take part in the final Nuclear Security Summit of Obama’s presidency last April, “the latest in a series of steps by Russia to end longstanding cooperation on nuclear security.” She said it was “disingenuous of Russia to cite the United States’ threat to strategic stability as a reason for this decision,” Trudeau said. “The United States seeks a constructive dialogue with Russia on strategic issues, but it is Russia instead who continues to engage in destabilizing activities.”

The breakdown of the accord has seemed possible for twenty years, as the Center for Public Integrity wrote in 2014. Almost immediately after President Bill Clinton and Russian President Boris Yeltsin agreed to limit and dispose of part of the two nations’ stocks of military plutonium, the U.S. preference for dilution and disposal and the Russian support for repurposing the plutonium as reactor fuel have been in conflict. Worries in Congress that Russia could produce and harvest more plutonium during the conversion process hung over the negotiations for about a decade, until South Carolina’s delegation in Congress finally swept those aside and persuaded Washington to approve a similar U.S. conversion plant in their state. Russia then rejected the Obama administration’s overture in 2009 to amend the disposal plan in a way that would have given the United States flexibility to draw down its plutonium stocks through other means.

So Putin’s decree isn’t a surprise.

At the same time, the Obama administration finds itself in the odd position of now being freed by Moscow to shift to a new approach – burial – that Congress hasn’t blessed. South Carolina’s politically powerful congressional delegation so far has beaten back the administration’s efforts to halt the MOX plant’s construction, keeping the project on life-support – a sort of low-speed construction – at a cost to federal taxpayers of around $350 million a year.

Ed Lyman, senior scientist at the Union of Concerned Scientists and a proponent of diluting and burying the excess plutonium, called on Sen. Lyndsey Graham (R.-S.C.), the fuel conversion plant’s chief congressional proponent, to give up the fight. “Graham has cited the U.S.-Russian agreement as the reason for his continued support of the MOX program,” Lyman said in a written statement. “Now there’s no excuse to continue building the plant.”