Anyone observing the republican movement's Easter commemoration in Belfast would have noticed colourful Basque flags, ironically rather like red, white and green Union flags, among the Tricolours and Starry Ploughs.
The members of Herri Batasuna (Popular Unity) who carried these flags up the Falls Road are supporters of ETA's 30-year campaign of violence to achieve full independence for the Basque country.
Their presence in Belfast had a particular significance this Easter: they want to be associated with the feelgood factor flowing from the Belfast Agreement. The association between Sinn Fein and Herri Batasuna (HB) goes back a long way. But the Stormont accord has brought that association into sharp focus in Spain, and reignited a debate about parallels between the Irish and Basque conflicts.
On the one hand, Basque nationalists, including the moderate majority who reject ETA's terrorism, hail the deal as a model for resolving their own problems. "The road followed by Ireland will also be the road taken by the Basque country," Arnaldo Otegi, an HB spokesman, declared at a rally in Pamplona. Demands for "Irish-style" negotiations were repeated, mantra-like, at less radical nationalist gatherings.
On the other hand, supporters of the 1978 Spanish constitution, which already concedes a large measure of autonomy to the Basques, insist that the Irish experience has little or no relevance in Europe's other "northern war". El Pais, Spain's most influential newspaper, described the Basque nationalist vision of the path to peace as an "Irish mirage".
Such abrupt dismissals of possible Irish parallels are not new. A year ago, writing in the foreign affairs journal Politica Exterior, Julio Trujillo said that "to compare both situations is like comparing the Lapps with the Zulu tribes of South Africa. Ireland and the Basque country are not the same."
To say this, however, is a truism which obscures, not only possibly significant similarities, but also the equally instructive differences. Likewise, the Basque nationalists' insistence on stressing parallels, often poorly understood, reflects a refusal to recognise the specifics of their own situation.
With each side trying to express the Belfast Agreement in terms of their traditional agendas, they might both be missing what is most remarkable about the Good Friday agreement: precisely the extent to which the contending parties have each had to abandon cherished dogmas in order to approach a settlement.
This was equally true, with all that that implies for good and ill, of the peace processes in South Africa and the Middle East.
Those who argue that the 1978 Spanish constitution is the ne plus ultra of concessions to peripheral nationalism have a point. Three of the four Spanish Basque provinces have an autonomous government, controlling much economic policy, culture, education and, increasingly, policing.
Imagine a Northern Ireland still within the UK, but run by the SDLP, with a police force largely made up of SDLP supporters, and you have a rough sketch of the Basque situation. Now try to imagine that nationalist police force coming under fire from the IRA, with unionist councillors also being systematically assassinated, and you may get some idea of its specific complexities.
A fourth province, Navarre, is regarded by Basque nationalists as the "mother province". "I know Navarre is Basque," an HB member once told me, "because I feel it in my blood". The province crudely approximates to a Northern Ireland within the Basque region, in that most of its inhabitants now feel more Spanish than Basque, but radical nationalists demand its incorporation into the Basque political entity, subject only to a referendum in all four provinces, regardless of the result in Navarre itself.
This is what ETA appears to mean by "self-determination", which it regards as the inalienable right of the whole Basque people. (Just where the three largely non-nationalist French Basque provinces fit into this process has never been clear).
Unlike Ireland, the Spanish constitutionalists argue, the Basque country was never colonised or invaded, but was absorbed into Spain as part of a "natural" process of nation-building. Nor was there ever any plantation of privileged Spanish settlers. In fact, Basque nationalism as a conscious political force developed largely in reaction to economic immigration by distinctly unprivileged Spanish workers from the 1880s onwards.
However, the Basques have not been the only Iberian people to adhere to nationalism in this century. Spanish fascism had a very aggressive nationalist component. The conservative and Catholic Basque nationalists took the surprising step of supporting the Spanish Republic against Franco's uprising, to defend their unique cultural and linguistic heritage.
Franco's civil war victory, followed by his ferocious repression of all aspects of Basque identity, made the sense of being colonised a real experience for many of the region's inhabitants for four decades.
It was in this context of "foreign" dicatorship that ETA was forged in the 1950s. While terrorist tendencies were always present, most of ETA's early actions were either quixotic, or targeted at notorious fascists. With the Spanish transition to democracy in the late 1970s (itself an exemplary "peace process") many members of ETA hung up their guns and joined normal politics. The remainder, however, pursued an increasingly indiscriminate terrorist campaign, killing far more people under democracy than they had under fascism.
Today, despite a series of military reverses in recent years, ETA's political support remains significant and solid, well over 10 per cent of the Basque electorate. It is indicative of declining militancy, however, that after the entire central committee of HB was jailed for collaboration with terrorism last December, there was little response on the streets.
Alongside a vicious campaign against local conservative politicians, ETA has increasingly targeted the Basque autonomous police and institutions, which has led to predictions of "a civil war among Basques". This is the opposite of Sinn Fein's convergence with the SDLP.
What then, ask Spanish constitutionalists, remains to be negotiated by democrats, apart from the dissolution of ETA and the subsequent release of its prisoners?
That, however, would be seen by ETA as surrender, and is unlikely to happen. It may be, though, that the Spanish majority is being disingenuous here. To build a peace process they may have to sacrifice some aspects of their own subliminal nationalism. Taking responsibility for the extensive use of torture and state terrorism in the 1980s would be a start.
To draw an analogy with the Downing Street Declaration, a statement that Spain had no "selfish or strategic" interest in the Basque country might also be helpful, and provide the context for a ceasefire.
It would, however, be very difficult for Madrid to make, and would make the Spanish army very unhappy. A process of "uncoupling statehood and nationhood", along the lines suggested in another context in a recent "World View", would help both sides to see things more clearly.
Meanwhile, the best lesson that ETA could learn from Good Friday is that an even more formidable terrorist group, the IRA, has given up unconditional demands and embraced real negotiation. It has put away its guns in order to do so, and gained political progress at home, and enormous international respect, as a result.