The Basque separatist group ETA's declaration Wednesday of a permanent cease-fire offers the prospect of an end to one of Europe's longest running civil conflicts, and a new constitutional future for Spain that could reshape the country's political map.
But the group's videotaped statement, aired on Spanish TV, marks only the first step toward resolving Madrid's thorniest challenge.
"The government's position is one of caution and prudence," Prime Minister Jose Luis Rodriguez Zapatero told parliament, responding to ETA's announcement. "Any peace process after so many years of horror and terror will be long and difficult."
The statement from ETA, which has been fighting for 40 years for an independent Basque state, explained the cease-fire - which goes into effect Friday - as a bid to "promote a democratic process in the Basque country ... in which our rights as a people will be recognized." The government, it warned "must recognize the results of this democratic process with no type of limitation."
Politicians had been speculating for weeks that the armed group, which has killed more than 800 people, was about to announce an end to its violent struggle. The government had repeatedly refused to open talks with ETA until it renounced the use of force.
Deputy Prime Minister Maria Teresa Fernandez de la Vega told the Senate Wednesday that the authorities would "work with all political forces" to bring peace to the Basque country, in Spain's Northeast. She said she hoped the cease-fire marked "the beginning of the end" of ETA, which stands for "Basque Homeland and Freedom" in the Basque language.
ETA has demanded that the Spanish government recognize the Basque country's right to declare independence, if a referendum in the region backs such a decision. Though Mr. Zapatero has ruled out such a move, his government has shown more tolerance of regional separatists than previous administrations.
On Tuesday, the Spanish parliament approved a new relationship between the central government and Catalonia, recognizing it as "a nation." Some observers suggested that the vote encouraged ETA to hope for a similar, or better, deal if it renounces violence. Last year, parliament authorized the government to hold talks with ETA, which is listed as a terrorist organization by the European Union and the United States, on the condition the group laid down its arms.
"If I was in ETA I would be optimistic" about the outcome of expected negotiations, says Florentino Portero, an analyst at the Strategic Studies Group, a think tank in Madrid. "Zapatero is a new generation of politician with a radically new way of conceiving of the state" as a confederation of sovereign regions.
On the streets of the Basque city of Bilbao, some citizens welcomed the news of the cease-fire. "I am very happy this has happened," says Inaki Muniain, a hotel receptionist, by phone. "This gives us hope that things will get better and that ETA will disappear or end up as a political party."
Echoing that optimism, Juan Avilés, expert in terrorism and security at the Universidad Nacional a Distancia "It's good news. It could really be the end of ETA's terrorism. You always have to be cautious when talking about terrorists, but I believe that this declaration could be the end of the nightmare that we've lived for almost 40 years."
Others were more cautious. "I don't believe it at all," scoffs Nestor Diez Seisdedos, a quality-control inspector at an electrical appliance factory in Barakaldo, also reached by phone. "It will last a while but it certainly isn't permanent."
Some analysts shared that skepticism. "ETA will maintain the peace as long as they consider it opportune," says Rafael Badarji, a security analyst with the conservative Foundation for Analysis and Social Studies in Madrid. "When it stops serving their aims they will pick up their weapons again."
Mr. Badarji says that ETA declared a cease-fire because "It believes ... its objectives will be better served politically than through force." After the Al Qaeda attack in Madrid on March 11, 2004, political violence such as ETA had used for decades appeared counterproductive. ETA has not launched any fatal attacks since 2003.
The Spanish police, supported by their French colleagues in the Basque regions across the French border, have also enjoyed considerable success in recent years. They have arrested over 750 ETA members, including top leader Mikel Antza, since 2000.
Wednesday's ETA video, showing three people sitting at a table in front of the ETA flag, their faces covered by masks and all wearing Basque berets, made no mention of any weapons handover. Nor did it offer to end the ETA practice of raising "revolutionary taxes" from Basque businessmen who have long complained of extortion.
The statement demanded that the Spanish and French governments "set aside repression," seen as a bid to persuade them to stop hunting ETA members.
One of the trickiest issues in any negotiations that the government opens with ETA will be the fate of the group's prisoners. ETA is expected to follow the example of other rebel military organizations from Northern Ireland to South Africa in demanding freedom for jailed comrades.
Such a move would doubtless be fiercely resisted by relatives of ETA's hundreds of victims, and by the conservative opposition People's Party. Party leader Mariano Rajoy accused Zapatero of "betraying the dead" when the Prime Minister first offered in 2005 to enter talks with ETA if it laid down its arms.
• Lisa Abend in Madrid and Asel Llana contributed to this article.
• What is ETA?
ETA stands for Euskadi ta Askatasuna, which means "Basque Homeland and Freedom." The group's aim is to establish an independent state for the Basque people, who have lived along the Spanish-French border since the Stone Age.
• When was the group formed?
ETA was formed in 1959 in response to Spanish dictator General Franco's suppression of Basque language and culture. When Franco died in 1975, the Basque Country was granted semi-autonomy. ETA wanted full independence.
• Whom does it target?
In its 40-year history, ETA has killed more than 800 people. Most of its attacks have been bombings or shootings, mainly targeting Spanish government institutions and personnel. The group is labeled as a terrorist organization by the United States and the European Union.
• Has it tried political means?
It has a political wing, Batasuna, but the Spanish government banned Batasuna in 2003. Since that year, ETA has not carried out any deadly attacks. It was originally blamed for the 2004 Madrid bombings, but Al Qaeda was found to be responsible.
Sources: Council on Foreign Relations; Institute for Counterterrorism; US State Department; and BBC.