President Bush's White House counterterrorism adviser said Wednesday that U.S. officials believe Al Qaeda wants to launch "a mass casualty, spectacular event" in the United States but don't think it can do so.

"Make no mistake, they're determined to figure out a way," said Frances Fragos Townsend. "So we work every day to make sure that doesn't happen."

Townsend, who went on the morning news shows to discuss the threat of terrorism a day after the administration released a chilling new National Intelligence Estimate, said, "The question is, do they have all the capabilities they need to do it and we don't think they have it yet."

• Click here to read the declassified National Intelligence Estimate (.pdf).

• Get complete coverage in FOXNews.com's War on Terror Center.

The report concluded among other things that Al Qaeda is using its growing strength in Pakistan and Iraq to plot attacks on U.S. soil, heightening the terror threat facing the United States over the next few years.

Prepared for President Bush and other top policymakers, the document lays out a range of dangers — from Al Qaeda to Lebanese Hezbollah to non-Muslim radical groups — that pose a "persistent and evolving threat" to the country over the next three years.

The findings focused most heavily on Usama bin Laden's Al Qaeda network, which was judged to remain the most serious threat to the United States. The group's affiliate in Iraq, which has not yet posed a direct threat to U.S. soil, could do just that, the report concluded. Al Qaeda in Iraq threatened to attack the United States in a Web statement last September.

In an interview Wednesday on CBS's "The Early Show," Townsend touted U.S. cooperation with Pakistan's President Gen. Pervez Musharraf and said the two countries continue to work closely together on the problem.

"There's no question that there's a very determined enemy that wants to come back and do us harm," she said. "What this report tells us, the American people have to understand, is that Al Qaeda is a determined enemy and we have to be equally determined to go after them."

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