WASHINGTON -- Riding high after two wars and notable successes against terrorist cells, U.S. officials had let confidence creep into the caution that had ruled their outlook on America's security since Sept. 11, 2001.
President Bush spoke of "19 months that changed the world." He declared the tide turned against terrorism. Without letting down their guard, officials spoke of al-Qaida being on the run, thwarted when it had tried to regroup.
Now the attack on compounds in Saudi Arabia illustrates what leaders also knew to be true -- military victories and the worldwide hunt for terrorists have eliminated neither the means nor the will to kill Americans for political purposes.
Victims of the terrorist attack in Saudi Arabia lived in guarded communities in one of the world's most heavily policed states. For all the vigilance, terrorists operating in the method if not the name of al-Qaida were able to pull off synchronized attacks, to deadly effect, using guile and common weapons.
"Our recent successes in Iraq, Afghanistan and in the global dismantling of terrorist cells may have understandably encouraged some Americans to begin to turn their attention away from the war on terror toward other pressing concerns," Sen. Jon Kyl, R-Ariz., who leads a Senate panel on terrorism and domestic security, said Tuesday.
The Saudi attack "is a reminder that our enemies will not be similarly distracted."
No one has declared the war on terrorism won, but there has been a growing sense America is winning it.
The absence of terrorist attacks outside Iraq during the war there -- despite exhortations, possibly by Osama bin Laden, to attack Americans in response to the invasion -- was taken as a sign by some administration officials that al-Qaida could not reorganize sufficiently to mount a major operation.
In his splashy visit to the USS Abraham Lincoln aircraft carrier earlier this month, Bush celebrated not only the U.S. victory in Iraq but wider achievement in making America safer. "The war on terror is not over, yet it is not endless," he said. "We do not know the day of final victory, but we have seen the turning of the tide."
FBI director Robert S. Mueller later said, "We have come a long way to create a seamless network of investigators and analysts that will intercept terrorists and terrorist plans."
Stan Bedlington, former CIA senior terrorism analyst and now a consultant, said the FBI, CIA and other agencies on the front line of the anti-terrorism struggle have not underestimated the risk of more attacks.
"Maybe at the top we got a little complacent," he said, meaning Bush and his most senior officials.
Indeed, U.S. intelligence sources have considered al-Qaida to be staggered but still capable. Bush contends that nearly half of the organization's senior operatives have been captured or killed. That means half or more are still thought to be free.
"I don't think that even the most optimistic thought that having al-Qaida 'on the run' meant having al-Qaida in total defeat," said Dan Byman, senior fellow at the Saban Center for Middle East Policy at the Brookings Institution.
"I would say that things are improving but improving does not mean victory."
The Saudi bombings came on the same day that authorities began America's first large-scale terrorism drills, deploying emergency workers to handle mock attacks by bioterrorism in Chicago and by a radiological dirty bomb in Seattle.
While preparing for such extraordinary dangers, the United States saw in Saudi Arabia what it has seen many times before -- that death and destruction from terrorism typically come in smaller doses, or with the most rudimentary instruments.
Even the Sept. 11 attacks, in a class of their own in scale and consequences, were pulled off with box-cutter knives, commercial airplanes and suicidal daring.
The United States cannot head off every danger like the ones that played out Monday night in Riyadh, Bedlington said.
"We can't cover the whole world," he said. "We should continue to persuade our allies to keep their guard up."
EDITOR'S NOTE -- Calvin Woodward has covered national affairs for The Associated Press since 1986.