We're bombarded with bad news -- the credit markets could freeze, millions more could lose their jobs, and today's recession could turn into a depression. But the danger we aren't hearing about could outweigh them all: the increased risk of a catastrophic terrorist attack.

A careful study of Osama bin Laden's videos, letters and Internet statements makes clear that Al Qaeda's goal is more than to terrorize Americans or to drive us out of the Middle East. Bin Laden believes that Al Qaeda can bring about the economic collapse of the United States -- and to achieve this goal, he has adopted a strategy of targeting America's financial centers and economic infrastructure.

Bin Laden cites the 9/11 attacks as proof that this strategy can succeed. In a November 2004 videotape broadcast on Al Jazeera, he boasted that Al Qaeda spent $500,000 on the event, while America lost, "according to the lowest estimate, $500 billion ... meaning that every dollar of Al Qaeda defeated a million dollars [of America] ... besides the loss of a huge number of jobs."

"America is a superpower, with enormous military strength and vast economic power," he concluded, "but all this is built on foundations of straw. So it is possible to target those foundations and focus on their weakest points, which, even if you strike only one-tenth of them, then the whole edifice will totter and sway."

The terrorists' ambitions are shaped by their experience fighting the Soviet Union in Afghanistan. Before the 9/11 attacks, Bin Laden said, "People used to ask us: 'How will you defeat the Soviet empire?' And at that time, the Soviet empire was a mighty power that scared the whole world. ... Today, there is no more Soviet empire. ... So the one God, who ... stabilized us to defeat the Soviet empire, is capable of sustaining us again and of allowing us to defeat America."

After 9/11, Bin Laden issued a letter warning the American people that our fate "will be that of the Soviets, who fled Afghanistan to deal with their military defeat, political breakup, ideological downfall and economic bankruptcy."

These statements tell us something important about the enemy: Although Bin Laden has many skilled bomb-makers and propagandists working for him, he lacks a single competent economist. Yes, the 9/11 attacks did cost America billions of dollars -- but our resilient free-market economy replaced every lost job within a few years. We would similarly recover from any other attack Al Qaeda might pull off.

But the terrorists don't have to be right to be emboldened. Clearly the daily news reports of our economic turmoil feed into Bin Laden's deep-seated belief that America is teetering on the economic brink -- and that with one big push, we can be forced into collapse. The financial crisis can only be serving to convince Al Qaeda that the time to strike America is now.

We have some factors working in our favor. The enemy has been weakened by our seven-year offensive against them. Our military removed Al Qaeda's haven in Afghanistan in 2001. With the "surge," we drove Al Qaeda from the new sanctuaries it had established in Iraq. And over the last year, America has put increasing pressure on Al Qaeda in its Pakistani stronghold. At least five of Al Qaeda's top operational planners met their end in that country in 2008, culminating on Jan. 1 when Usama al-Kini, Al Qaeda's chief of operations in Pakistan, and his lieutenant, Sheikh Ahmed Salim Swedan, were killed. This is the highest pace of strikes against senior Al Qaeda operational planners since the war on terrorism began.

Another factor working in our favor is the severity of the 9/11 attacks. In striking the Twin Towers and the Pentagon, Al Qaeda set an extremely high bar for itself. If it launched an attack that did not meet that bar, it would be seen as a sign of weakness. This is likely why we have not seen smaller-scale attacks on shopping malls and other "soft" targets during the last seven years. By contrast, this also means that, whatever the terrorists are now planning, it likely will be on a scale to equal, or even dwarf, the attacks of 9/11.

Al Qaeda's failure to strike America after seven years creates pressure on the terrorists to act. The lack of another catastrophic attack on the United States, combined with the massive defeat terrorists have suffered in Iraq, sends a message to the Muslim world that Al Qaeda is losing its war with America. The terrorists need to pull off something spectacular to prove that they are still a force and a threat. Al Qaeda's growing desperation to strike America, and our perceived growing vulnerability, are a dangerous combination.

All this means that now is no time for President Obama to begin dismantling the institutions President Bush put in place to keep America safe. Obama needs to recognize that, at this moment, somewhere in the world, the terrorists are watching the economic turmoil in our country -- and planning an attack they believe will bring our economy to its knees. In the face of this danger, America must not let down its guard.

Marc A. Thiessen held senior positions in the Pentagon and the White House from 2001 to 2009, most recently as chief speechwriter for President George W. Bush.