WHEN ETA, the Basque separatist group, decided to show how it might put its arms out of harm’s way, it produced only a token sample of the weapons used to kill more than 800 people. This consisted of three pistols, a Heckler and Koch G3 rifle, a handful of detonators and some half-kilo bags of explosives, which were shown in a video released on February 21st. The sample was presented by masked ETA members to unofficial mediators who subsequently announced that one of Europe's bloodiest terrorist groups was now ready for full decommissioning. But was this just ETA propaganda, aimed at forcing Spain’s government to negotiate?

That is what the Popular Party (PP) of Mariano Rajoy, the prime minister, concluded after mediators unveiled what they called the first-ever example of ETA arms being put “beyond operational use”. “They came here to lie to us,” said Esteban González Pons, PP vice-secretary. Two days after the announcement, the mediators were called before a magistrate in Madrid to explain themselves. Among those backing them was the regional prime minister of the moderate Basque Nationalist Party. He sees disarmament as central to healing the wounds left by 40 years of bloodshed.

In 2011 ETA called a permanent, unilateral ceasefire. Mr Rajoy has offered it nothing in return, at least officially, and refuses to negotiate an arms handover. ETA has proved an unreliable negotiating partner in the past, in particular when it broke an earlier ceasefire by killing two people at Madrid’s airport in 2006. No Spanish government has trusted it since. By the time it called its current ceasefire, it was operationally bust and had lost much of its support in the Basque country. It was, in effect, defeated.

Yet that defeat has to be managed. ETA is being urged to disarm unilaterally by separatist parties that have emerged successfully from its shadow since the ceasefire. But ETA has no one to hand arms to. Jorge Fernández Díaz, the Spanish interior minister, says it can tell police where its arms are stocked. ETA is unlikely to do that, because it would give police clues as they pursue its remaining members. The mediators offer a safe set of neutral hands. The trouble is that they need the government’s support. The task of gathering hundreds of weapons is almost impossible unless Mr Rajoy asks the authorities in France (where the arms are mostly hidden) to turn a blind eye.

Will that happen? Not until after European Parliament elections in May in which the PP faces opposition from vociferous anti-ETA rightists. And not before ETA makes it clear that it really wants nothing in return.