The series of "spectacular" attacks carried out by ETA over the past 10 days have not only cost a human life, destroyed property and deeply embarrassed the Spanish Interior Ministry, they have also widened the fracture between the Madrid-based Spanish parties and moderate Basque nationalists into a chasm which will be very difficult to bridge.
Earlier this week, the Spanish Prime Minister, Mr Jose Maria Aznar, accused some (unnamed) Basque nationalists of "writing the vilest pages in Spanish history". He was not referring to ETA, but to those moderate nationalist leaders who have participated in the construction of post-Franco Spanish democracy. Even setting aside his hyperbole - Mr Aznar would otherwise appear to be suffering from chronic historical amnesia about, for example, Gen Franco and the Holy Inquisition - his words indicate the depth of the rupture that has developed between Spanish and Basque nationalist democrats over the past two years.
Mr Aznar was responding to equally contentious comments from Mr Xabier Arzalluz, president of the Basque Nationalist Party (PNV). Mr Arzalluz, a former Jesuit whose ambiguity about ETA's violence infuriates Madrid, had implied that Mr Aznar's Partido Popular government bore some responsibility for the revived terrorist campaign. The PP, he said, had failed to negotiate meaningfully with ETA during the 1998/1999 ceasefire. Mr Arzalluz has a point, but it was hardly likely to be accepted by the PP leader while one of his local councillors was being buried in Malaga after been shot in front of his wife and daughter by ETA. The PNV is explicitly excluded from ETA's long list of "legitimate" targets. The PP, and the opposition Socialist Party (PSOE), contend that Mr Arzalluz's party is the source of oxygen for ETA's terrorism, by refusing to stop collaborating with ETA's political wing, Herri Batasuna.
This is a dialogue of the deaf, which ETA is exploiting skilfully. Its revitalised terrorist infrastructure has left the Spanish security forces looking rather helpless. Several bungled operations last December, when it ended its 15-month ceasefire, left the impression it was a terminally weakened force. Since last January, however, it has carried out a series of killings and bombings, building up the campaign this summer to a rhythm reminiscent of the dark days of the early 1980s.
But no one should forget this "military" campaign has a political goal: a definitive break between nationalists and non-nationalists in the Basque country which would drive the moderate nationalists into ETA's camp.
ETA is closer to achieving this than ever before, but the relationship between Basque nationalists and Spanish democrats has never been an easy one. When the landmark 1978 democratic constitution was put to referendum, the PNV was the only democratic party to refuse to support it. The constitution, the PNV argued, did not adequately recognise Basque sovereignty. Unlike every other Spanish region, only a minority of the Basque's electorate voted for that constitution.
However, the PNV then accepted a statute of autonomy within the limits set by that constitution in 1979 and has dominated the powerful Basque regional government ever since. ETA regarded this compromise as treachery and continued to use terrorism in pursuit of an independent Basque country, with the support of a significant minority of Basques. Faced with this threat, the PNV came to present a (more or less) united democratic front against terrorism with the PSOE and PP. The unresolved issue of Basque self-determination, however, made this alliance an uncomfortable one.
Finally, the PNV made a radical shift in the late 1990s, and signed the "Lizarra Pact" with Herri Batasuna, in September 1998. Lizarra was effectively a manifesto for Basque self-determination.
Less than a week later, ETA announced, for the first time in its 40-year history, an "indefinite ceasefire". There was euphoria in the Basque nationalist camp, but in Madrid both the PP and the opposition Socialists responded with deep suspicion.
The Lizarra Pact was explicitly based on a study of the Northern Ireland peace process. There was optimism on the nationalist side that a pan-nationalist front, similar to the Hume-Adams axis with Fianna Fail, could extract a "Downing Street-style" declaration from Madrid. Herri Batasuna, under its charismatic new leader Arnaldo Otegi, began to articulate a much more flexible political line, with some assistance from Sinn Fein's spin doctors.
The radicals made immediate electoral gains, surging from 166,000 votes to 233,000 in October regional elections, a result which seemed likely to keep ETA's guns silent for the foreseeable future. Closer study of the those elections, however, revealed a picture much less favourable to the nationalist strategy. A large minority of Basques have no nationalist sympathies, and the sharpest rise in votes was enjoyed by the PP, deeply hostile to the Lizarra Pact. It became the second biggest party in the Basque parliament. The Socialists, almost equally anti-Lizarra, also did well. The prospect of a non-nationalist Basque government opened up for the first time.
Meanwhile, the gains made by the moderate nationalists ranged from modest to insignificant. The PNV had to rely on the support of ETA's political wing to form a government in a Basque parliament edgily balanced between supporters and opponents of Basque self-determination.
The subsequent ceasefire period confirmed the rupture between the moderates and Madrid. The defenders of the Lizarra Pact accused the Madrid-based parties of being unwilling even to entertain the idea of Basque sovereignty. Madrid accused the moderate nationalists of having adopted ETA's programme as its own as the price for its parliamentary support. And the Interior Minister, Mr Jaime Mayor Oreja, himself a Basque, repeatedly insisted that ETA's ceasefire was simply a "trucetrap". It was designed, he said, to enable a greatly weakened terrorist group to rearm and reorganise.
MR Aznar at first seemed open to other advisers, who told him there was real shift away from violence among ETA supporters, and the truce was an opportunity which should be grasped imaginatively. In the end, however, Mr Oreja's "police" policy prevailed, with continuing detentions of ETA suspects and foot-dragging on prisoner issues. Government contacts with ETA did occur abroad, but they were unproductive, according to both sides.
By this time last year, ETA was making its displeasure known at the lack of progress. Interestingly, the group reserved its most caustic criticisms for its moderate nationalist allies, which it accused of failing to pursue Basque sovereignty with sufficient vigour. In December, it announced a return to the campaign, which has escalated throughout this year.
The PNV has remained isolated ever since. While it has abandoned most regional and many local links with ETA supporters, it refuses on principle to back down on the demand for self-determination. Meanwhile, Mr Aznar's party has seen the opportunity to dislodge the PNV's minority government in the Basque Country, with a groundswell of revulsion against ETA's renewed campaign.
Early regional elections are now likely in the autumn, and they could well produce a non-nationalist PP-PSOE coalition to run the Basque autonomous institutions.
While this is a perfectly legitimate democratic option, it would be anathema to many moderate nationalists, and might produce the new phase of polarisation which ETA's strategy seeks. The bitter irony is that none of the democratic parties, nationalist or non-nationalist, seem to be able to stop speaking the bitter words dictated by ETA's own script.