MADRID — The trial of eight Britons charged with plotting to blow up transatlantic flights ended in London this week with a mixed verdict. But to anti-terrorism officials, two things are clear: The 2006 plot was an ambitious effort by Al Qaeda to match the carnage of the Sept. 11 attacks.
And it failed.
Today's seventh anniversary of the attacks on the United States finds anti-terrorism officials optimistic that they have damaged Osama bin Laden's network and its offshoots, but wary of the evolving nature of the threat.
Newly disclosed intelligence illustrates that the airplane plot was part of a broader campaign. British anti-terrorism officials said information that couldn't be used in court linked the plot to the bombing of the London transportation system in July 2005 and a failed follow-up attack two weeks later. Intercepts and other evidence indicate that leaders of the plots had contact with each other, converged in Pakistan and were trained by Al Qaeda bosses, officials said.
But only the first attack, which killed 52 people on the public transportation network, succeeded.
Because a foremost objective of Al Qaeda has been to strike in the West, the absence of attacks since 2005 appears to reflect the network's weakened state. Its North African offshoot wages a deadly campaign in Algeria, but has done little elsewhere. Fears about returning fighters from Iraq targeting the West have not materialized. Bin Laden and his deputy, Ayman Zawahiri, are still fugitives and are thought to be in Pakistan. But a barrage of U.S. missile strikes near the Afghan border has slain at least three of their frontline operational chiefs this year.
"It's clear that pulling off big attacks is more difficult," said a senior European police official who requested anonymity because of the sensitivity of his work. "The police have gotten better. Intelligence services have penetrated the networks. They have the desire to attack, but whether they have the capacity is less clear."
Still, anti-terrorism forces are on guard.
Al Qaeda's core leaders, and forces including foreign militants and Taliban fighters waging war in Afghanistan, have carved out a sanctuary in northwest Pakistan. The flow of militants that originates in the Muslim world and Europe has shifted its destination from Iraq to the Pakistan-Afghanistan border zone. The Internet has contributed to the rise of a generation of homegrown extremists. And past major attacks by Bin Laden's network took years to prepare.
"We don't want to let complacency sink in. That is exactly when something can happen," said a senior British anti-terrorism official. "The threat hasn't manifested itself in the West recently, but the picture looks a lot different if you are in Algiers or Islamabad."
The timing of terrorist attacks is dictated largely by logistics, targets and anniversaries of significance to extremists. Although Bin Laden interjected himself into the U.S. electoral debate in 2004 by releasing a video days before the presidential vote, the Western political calendar seems to have little effect, according to anti-terrorism officials.
A historic exception: Train bombings here in 2004 killed 191 people and influenced the Spanish elections three days later. The Madrid attacks displayed the devastating capacity of a makeshift cell with only indirect links to the broader Bin Laden network.
With the U.S. presidential election campaign in its homestretch, officials say they will heighten their vigilance. European anti-terrorism officials say they expect a final push by the Bush administration to capture or kill Bin Laden and top deputies. And the start of the countdown to the Nov. 4 election coincides this year with the Muslim holy month of Ramadan. Although Ramadan is a period of reflection and prayer for most Muslims, it can also spur extremists to action.
"The analysis takes the American elections into account," said veteran anti-terrorism prosecutor Stefano Dambruoso, now director of international programs for Italy's Justice Ministry. "The threat could be from 'Qaedists' -- Internet radicals who are not directly in contact with Pakistan -- or directly from Al Qaeda. More likely the first than the second."
Al Qaeda remains determined to strike on American soil, anti-terrorism officials say. But it has run up against aggressive surveillance, tough border security and a lack of extremist communities in which to operate. Instead, officials say, it appears to have focused on using Europe to hit targets such as the flights bound for the United States from Britain.
Europe has its own worries. After Madrid and London were hit, Italy and France seemed vulnerable. But thus far, a crackdown on the European mainland has prevented any plot by widespread networks of North African militants from reaching advanced stages.