Last October, dozens of House progressives were slapped down by the US foreign policy establishment for floating, in the words of one congressional staffer, “the softest trial balloon about diplomacy” to end the Ukraine war. The episode seemed to slam the door shut on even the mildest progressive dissent from White House policy on the war, with the nine months that followed defined largely by lockstep Democratic support for the administration’s wishes, with only a relatively small cohort of Republicans defying the president in the form of voting against further military aid.

But President Joe Biden’s decision earlier this month to approve the transfer of cluster munitions for use by Ukrainian forces may have opened that door a crack. Last night, in a failed 147-276 House vote to ban the provision of the notoriously child-maiming weapons, forty-nine Democrats and ninety-eight Republicans voted for an amendment to that end brought forward by Rep. Marjorie Taylor Greene (R-GA). Despite the roughly 2-1 margin against Greene’s measure, the vote marks one of the most significant congressional challenges to the Biden administration’s approach to the war since the Russian invasion last February, and is certainly the most substantial episode of progressive dissent from the White House on the matter.

The vote is doubly significant given the underhanded maneuvering that took place to kill its backing. The original National Defense Authorization Act amendment to block the White House’s cluster munitions transfer — one that Biden is embarking on using a loophole to get around an unambiguous legal ban on sending the deadly civilian-killing shells — was put forward by two Democrats, Reps. Sara Jacobs (D-CA) and Ilhan Omar (D-MN) and was accompanied by a letter from them and seventeen other House Democrats renouncing the move.

Erik Sperling, the executive director of Just Foreign Policy who has been working on drumming up support for halting the cluster munitions transfer, estimated there would have been considerable bipartisan support for the amendment had it gone to the floor. “They got very nervous,” he says. “It was looking extremely likely that we could pass this.” As evidence, Sperling points to recent statements from the Senate, with Sen. Bernie Sanders (I-VT) alluding to a companion effort in the upper chamber to ban the weapons, and Sen. Tammy Duckworth (D-IL) vowing to “work very hard to oppose” the Jacobs amendment if it passed the House.

The amendment drew bipartisan support, with the Donald Trump–aligned Matt Gaetz (R-FL), who has shown an appetite for working with progressives on antiwar legislation in the past, cosponsoring the amendment. This cross-ideological backing reflected an unusual amount of opposition to Biden’s announcement, which has been criticized by human rights groups and was met with polite nonsupport from even close US allies like the UK and Germany.

To weaken support for upholding the ban on the weapons, whose use was last year declared a war crime by the White House press secretary, House Republicans embarked on a clever gambit. All nine GOP members of the House Rules Committee voted down the Jacobs-Omar amendment and instead advanced Greene’s as the one that would get a floor vote.

From the point of view of lawmakers eager to to litter eastern Ukraine with cluster bomblets, Greene’s amendment had two advantages: it applied only to cluster munition transfers in Ukraine, turning the vote into a referendum on the war, which is most enthusiastically backed by Democratic voters; and it was attached to the politically toxic Greene, an unpopular, formerly QAnon-supporting Republican congresswoman who is hated by liberals and was just booted from the stridently right-wing Freedom Caucus.

As a result, a number of Democrats who had expressed discomfort and even outright opposition to Biden’s move effectively voted to uphold it. That includes Jacobs, the original sponsor of the Democratic anti–cluster munitions amendment who simply chose not to vote on Thursday, as well as three other signers of the House progressive letter against the weapons: Sheila Cherfilus-McCormick (D-FL), Hank Johnson (D-GA), and Sheila Jackson Lee (D-TX), who voted “present.” Other Democrats who had spoken out against the White House’s move but failed to follow through last night include Reps. Jason Crow and Unexploded Ordnance and Demining Caucus cochair Chrissy Houlahan (“victory cannot come at the expense of our American values and thus democracy itself”).

Yet despite the political risks and major pressure to vote against the Greene amendment — including a rhetorical upping of the ante from Secretary of State Tony Blinken, who claimed Ukraine would be left “defenseless” if the munitions were blocked — many progressives and others stuck to their guns. Several lawmakers contacted by Jacobin in advance of the vote indicated they would back Greene’s amendment and followed through. That included Republican representative Dan Bishop (“I think it’s reprehensible”) and Democratic congressman Rick Larsen (“More than 120 countries have banned cluster bombs. The United States must do the same”), as well as democratic socialist Squad member Rep. Greg Casar (D-TX), who had earlier warned that “we don’t want to indiscriminately harm children and families and civilians,” and progressive Rep. Chuy Garcia (D-IL).

“I support the approach of the Jacobs amendment, which focused on the use of these weapons, not the country where they are used,” Garcia told Jacobin. “Still, I oppose this sale and every other sale of barbaric cluster munitions, and I will take every opportunity to prevent civilian death, including this one.”

In the end, every member of the Squad and others associated with the cohort of young socialists and progressives — including longtime members Reps. Omar, Alexandria Ocasio-Cortez (D-NY), and Rashida Tlaib (D-MI), as well as more recently elected figures like Summer Lee (D-PA), Maxwell Frost (D-FL), and Becca Balint (D-VT) — held the line despite the shenanigans. Rep. Barbara Lee (D-CA), a longtime congressional critic of US foreign policy and an outspoken opponent of the cluster munitions transfer also voted for the amendment, as did Rep. Ro Khanna (D-CA), one of the signers and vocal defenders of the progressives’ pro-diplomacy letter last year, who said that “thousands of kids will die because of cluster bombs,” and that he voted “based on the issue, not the author.”

Even some surprising names voted in support, signaling the depth of discomfort with the White House’s decision. Rep. Jamie Raskin (D-MD) had been one of the more vocal members to renounce the October letter he had signed, yet voted for Greene’s amendment. Maybe the most surprising vote in favor was Adam Schiff (D-CA), who has built a political brand as one of the most strident anti-Russia hawks in Congress and is currently running against Lee and Rep. Katie Porter (D-CA) — another “aye” vote last night — for a California Senate seat. Even House Ukraine caucus cofounder and cohair Rep. Marcy Kaptur (D-OH) chose to vote “present” rather than an outright “no.”

Sperling says that while the strategy to associate the push with Greene was “novel and, frankly, impressive,” it was also a risky maneuver that let both members of Congress and activists familiarize themselves with the Blob’s tactics, something they had already been doing during eight years of fights over the Yemen War. “Every time that the White House and committee leaders have to scramble to respond to a pro-restraint initiative in Congress, the inside-outside movement learns more about the tools and tactics that hawks can use to stymie democratic participation and progress,” he says. “Members and advocates will be less susceptible to this gimmick going forward.”

Of course, this still means that the majority of the House, including most Republicans and Democrats, voted in favor of sending cluster munitions for use by Ukrainian forces, which means the outcome that critics have been warning about — of Ukrainian territory booby-trapped for years to come with tiny explosives that will kill and mutilate innocents — is the likely outcome. It’s the latest in a long line of decisions from ostensibly friendly governments detrimental to the welfare of ordinary Ukrainians that are sold as being in their favor, from early US and British opposition to peace talks in favor of pursuing military victory against Russia to the recent decision to provide Ukrainian forces with toxic depleted uranium rounds linked to cancers and birth defects.

Nevertheless, the vote may signal a watershed in official progressive discourse on the war, which has been stifled for the better part of a year and a half by an often vicious pressure campaign of smears and jingoism. Whether that’s the case depends on what progressives decide to do next. Perhaps it’s time to dust off that pro-diplomacy letter.