It will be some time before the authorities in Madrid and Washington sort out the question of exactly who is and isn’t responsible for the bombings that killed at least 192 persons and wounded 1,200 in Madrid yesterday. Even while the Spanish government was blaming the Basque separatists, known as the Euskadi Ta Askatasuna (a position echoed by Secretary Powell), the spokesman for the ETA’s political wing, Arnaldo Otegi, was putting out a denial, saying, “The independent Basque left cannot imagine there is even a hypothetical chance that ETA could be behind what happened in Madrid.” In other words, the London Daily Telegraph noted, the killings were “so nihilistic and so contemptuous of human life as to shock even those who normally regard attacking civilians as a legitimate political tool.”

The smell of cordite was still engulfing Madrid when the Associated Press moved a story quoting the Arabic newspaper Al-Quds as saying it had received a claim of responsibility issued in the name of Al Qaeda. The e-mail, signed by the shadowy Brigade of Abu Hafs al-Masri, was, the AP said, received at the newspaper’s London offices.

“This is part of settling old accounts with Spain, the crusader, and America’s ally in its war against Islam,” it said. Spain’s security forces were not ruling out “any line of investigation,” the AP said. Spain, of course, had backed the American-led war on Iraq despite domestic opposition, the AP said, noting that many Al Qaeda–linked terrorists have been captured in Spain or were believed to have operated from there.

One of the facts underlining suspicion against the Basque terrorists is that the bombing came three days ahead of Spain’s general election, in which the question of how to deal with the ETA was a major issue. The election campaign was called off for three days. The wires were noting that if the attack was carried out by the ETA it could signal a radical change of strategy for a group that has largely targeted police and politicians.

Police found a stolen van with seven detonators and an Arabic-language tape parked in a suburb near where the stricken trains originated, which prompted the authorities to put out their statement that they did not rule out any line of investigation.

The ETA spokesman, in denying that the Basque group was responsible, blamed the crime on the “Arab resistance,” phrasing that indicated sympathy for the Islamic terrorists. This underscores an under-appreciated fact in the current war: that terrorists fighting ostensibly different causes often cooperate, and it would be naïve to rule out ETA’s cooperation with Al Qaeda. Seemingly disparate terror organizations have worked together in the past.

For years, Yasser Arafat was on the payroll of numerous eastern European intelligence services. The timer used in the 1989 bombing of the Pan Am 103 jetliner, a Libyan operation, was made by an outfit with ties to the Irish Republican Army. In 2001, Colombian authorities found Irish terrorists running guns for the FARC and seeking refuge in Cuba.

Today, mounting press and intelligence reports indicate that Hezbollah agents from Lebanon are establishing a base in the tri-border region of South America. For years, conferences in Beirut featured terrorists of all stripes, with no common cause other than their willingness to kill innocent civilians to further their political agendas.

These kinds of cooperation are something that the intellectuals on the left don’t like to admit, which is one reason there has been such animated derision of the evidence that Al Qaeda and the Baathist regime in Iraq were in cahoots. Admit to these entanglements among the terrorists and one can end up delegitimizing a lot of causes with which the left has linked arms over the years. These sorts of entanglements are certainly part of the terrorist scene in Spain.

Which will lead many Americans to think of Spain with special affection and growing sympathy in these coming months. An act of “barbaric terrorism” is the way the attack yesterday was described by the Spanish monarch, Juan Carlos.

President Bush telephoned the king to convey America’s sympathy. “I told them we weep with the families, we stand strong with the people of Spain,”Mr. Bush said. He also put in a call to Prime Minister Aznar, who had supported us so staunchly during the Battle of Iraq, to which Spain sent 1,300 troops.

Mr. Bush is often lambasted by the American left for saying that nations are either with us or against us in the fight against terror, and it is important for him to let Spain know that we comprehend the emotions they are going through after this attack. And it is also important to remember that terrorists try to conceal their affiliations with other terrorists and the states that support them.