The Big Question: Why is Eta killing people in France, and will it ever lay down its arms?

Why are we asking this now?

A Spanish Civil Guard, Raul Centeno, was killed and another colleague, Fernando Trapero, badly injured by Eta terrorists in Capbreton, south-west France, on Saturday. It is the first such attack by Eta in France since 1976. The officers went into a caf in which three Eta terrorists were sitting by chance. The terrorists are believed to have been preparing an attack in Spain. Spanish officers routinely mount plain-clothes anti-terrorist operations with French counterparts in France. In this case, the unarmed officers tried to arrest the fleeing terrorists and were shot.

What is Eta's struggle all about?

Eta is an acronym for Euskadi Ta Askatasuna, or Basque Homeland and Freedom. Its members want an independent Basque state in north-west Spain and south-west France. The group began in 1959 by advocating Basque cultural values before evolving into an armed group with Marxist and Leninist ideals. The group is proscribed as a terrorist organisation by Spain, France, the UK, the EU, the US and the United Nations. Over nearly half a century its first attack is thought to have been in 1961 it has killed more than 800 people.

Who are the Basques?

The Basques inhabit north-west Spain and south-west France. The name Basque comes from medieval French. There are thought to be about 5m Basques in both Spain and France. About 25-30 per cent of the population of the Spanish Basque Country speak Euskara or Basque. This language, which was banned during the dictatorship of General Francisco Franco because it was a symbol of independence, is not known to come from any other European language. It enjoys co-official status with French and Spanish and has been around longer than any other European languages. The Basque country has its own government and police force and enjoys considerable autonomy from Spain. Only a small minority supports Eta.

What is Eta'scurrent strength?

Eta is said to be made up of about 100 active volunteers. It has a "logistical" wing which supports the terrorist cells that mount attacks. Successive arrests and convictions have greatly weakened the organisation in recent years.

A change in French government policy to support Spain in anti-terrorist operations has been crucial in that process. Until the 1990s, France had refused to cooperate in the fight against Eta because of a state-sponsored "dirty war" launched during the 1980s by Spanish police and mercenaries. Now security services from both countries co-operate. Still most Eta leaders hide in France where the police presence is not as heavy as in Spain.

What have been Eta's most notorious acts of terrorism?

In 1987 Eta bombed a supermarket in Barcelona, killing 21 people. Ten years later, it abducted and then shot dead the councillor Miguel Angel Blanco after the government refused to give in to its demands to move all Eta prisoners closer to the Basque country. The murder brought thousands on to the streets in spontaneous protests and lost the terrorists a large deal of support.

In 1973, Eta mounted an audacious car bomb attack in Madrid, assassinating Prime Minister Admiral Luis Carrero Blanco, the nominated successor to dictator General Francisco Franco. It also attempted to kill King Juan Carlos and former Prime Minister Jose Maria Aznar in 1995. Aside from shootings and bomb attacks, it finances itself by extorting cash from businesses in the Basque country. Its supporters also mount regular riots against the police.

Have there not been frequent ceasefires?

Eta has declared ceasefires 11 times. The last time it called for a truce was in March 2006, when the terrorist group said this was a "permanent ceasefire". Commentators said that the general revulsion against terrorism after the 9/11 attacks in the United States and the Madrid train bombings in 2004, in which 191 people were killed by Islamic terrorists, combined with a series of key arrests of Eta leaders, had forced the group to come to the negotiating table.

But the ceasefire did not last. In December 2006, Eta bombed Madrid Barajas airport, killing two Ecuadorian immigrants. The separatists "officially" ended the truce in June this year.

Why did the most recent talks end?

Eta blamed a breakdown in talks on problems in negotiations with Prime Minister Jose Luis Rodriguez Zapatero's Socialist government. Despite a series of talks between the Spanish government and Eta leaders in secret locations outside Spain, the sticking point was that Eta would not give up violence.

Zapatero, who came to power in 2004 promising a Northern Ireland-style peace deal, was also weakened by lack of support from the conservative opposition Popular Party, which refused to have anything to do with the Basque separatists until they laid down their guns. Unlike in Britain, where both Labour and the Conservatives operated a united front against the IRA, Spain's main political parties are bitterly divided over the issue of Eta.

Does the approach of the current Spanish government differ from predecessors?

Zapatero made one key change in the way Madrid has dealt with Eta. He introduced a law in 2005 which allowed the government to hold direct talks with the armed Basque separatists. Previously, Spanish governments were forced to hold secret talks with Eta, as the law prevented any contact with the terrorist organisation. After the new law was introduced, Zapatero announced the talks would go ahead amid widespread condemnation from the conservative opposition and victims' groups. But other parties supported the peace negotiations.

How are the French likely to react?

French authorities are hunting the two men and a woman who carried out the attack on the Spanish police officers. They may intensify their operations against Eta and its safe houses in France in the coming months. Arrests of Eta leaders and operatives routinely take place in France and trials are held in Paris. France also speeded up the way Eta suspects can be extradited to Spain in order to make it easier for Madrid to try alleged terrorists.

Though the issue of Eta does not attract the same attention in France as in Spain, the murder in France may focus the French government on the need to crack down still further.

So can Eta be defeated?

Yes

* The terrorists have been so weakened by continued arrests, they can be beaten by the Spanish security services

* Grass-roots support is dwindling, and it is reduced to villages which Eta calls its heartland

* If Madrid takes a dramatic political gamble, it could find a peace deal by outmanoeuvring Eta

No

* A hardcore element of support exists within Eta which will keep the group going

* As older leaders renounce violence, younger members take their place, ensuring that the military apparatus continues

* Despite 40 years of struggle, Spain and France have still not defeated Eta