Homeland Security Forecasts 5-Year Terror Threats

"The threat of terrorism and the threat of extremist ideologies has not abated," Chertoff said in his year-end address on Dec. 18. "This threat has not evaporated, and we can't turn the page on it."

These high-consequence threats are not the only kind of challenges that will confront the U.S. over the next five years.

Terrorists will continue to try to evade U.S. border security measures and place operatives inside the mainland to carry out attacks, the 38-page assessment said. It also said that they may pose as refugees or asylum seekers or try to exploit foreign travel channels such as the visa waiver program, which allows citizens of 34 countries to enter the U.S. without visas.

Long waits for immigration and more restrictive European refugee and asylum programs will cause more foreigners to try to enter the U.S. illegally. Increasing numbers of Iraqis are expected to migrate to the U.S. in the next five years; and refugees from Somalia and Sudan could increase because of conflicts in those countries, the assessment said.

Because there is a proposed cap of 12,000 refugees from Africa, officials expect more will try to enter the U.S. illegally as well. Officials predict the same scenario for refugees from Afghanistan, Bangladesh and Pakistan.

Intelligence officials predict the pool of radical Islamists within the U.S. will increase over the next five years due partly to the ease of online recruiting means. Officials foresee "a wave of young, self-identified Muslim 'terrorist wannabes' who aspire to carry out violent acts."

The U.S. has already seen some examples of these homegrown terrorists. Recently five Muslim immigrants were convicted of plotting to massacre U.S. soldiers at Fort Dix in a case the government said demonstrated its post-Sept. 11 determination to stop terrorist attacks in the planning stages.

The Lebanese Shiite group Hezbollah does not have a known history of fomenting attacks inside the U.S., but that could change if there is some kind of "triggering" event, the Homeland assessment cautions.