Washington ? Six years after the deadliest terrorist attack on American soil, the United States in many ways is unprepared to stop another major strike against the homeland, which al-Qaida appears intent on carrying out in the near future, four of the nation’s top counterterrorism officials told Congress on Monday.

Al-Qaida’s intentions have been underscored in recent days by the disruption of suspected terrorist plots in Germany and Denmark, the first videotaped propaganda tape by Osama bin Laden in three years and persistent intelligence showing that the terrorist organization has regrouped in a safe haven in Pakistan and actively trains operatives there to launch attacks worldwide.

“Our counterterrorism efforts have disrupted some of the enemy’s plans and diminished certain capabilities,” John Scott Redd, the director of the National Counterterrorism Center, told the Homeland Security and Governmental Affairs Committee. “But the events of the last days and the last weeks clearly demonstrate the clear and present danger which continues to exist.”

During more than three hours of prepared testimony and questioning, Homeland Security Secretary Michael Chertoff, Director of National Intelligence Michael McConnell, FBI Director Robert Mueller and Redd said significant progress has been made in deterring another attack on the scale of Sept. 11, which killed nearly 3,000 people.

U.S. intelligence-gathering efforts against terrorist targets have improved dramatically , in part because of expanded post-Sept. 11 electronic surveillance powers, including those overseen by the Foreign Intelligence Surveillance Act, or FISA, according to McConnell.

Confirming a Los Angeles Times report, McConnell told the committee that U.S. electronic intercepts were instrumental in helping thwart the terrorist plot last week in Germany, which allegedly involved militants trained in Pakistani camps run by an al-Qaida affiliate group known as the Islamic Jihad Union.

The surveillance “allowed us to see and understand all the connections … to al-Qaida,” McConnell said. “Because we could understand it, we could help our partners through a long process of monitoring and observation, realizing that the perpetrators had actually obtained explosive liquids… “

After the hearing, Redd confirmed that such U.S. intercepts also played a central role in disrupting the suspected terror plot in Denmark, in which eight men with alleged al-Qaida links were arrested on suspicion of plotting a “major” attack.

McConnell said some of those capabilities were the result of a “temporary fix” in the FISA law passed by Congress in August in an attempt to maintain the surveillance system while addressing some of its legal problems. He said he believes that FISA itself is in jeopardy because of concerns that intelligence officials are “spying on Americans, doing data-mining and so on,” which he said was “simply not true.”

“If we lose FISA, we will lose, in my estimate, 50 percent of our ability to track, understand and know about these terrorists, what they’re doing to train, what they’re doing to recruit and what they’re doing to try to get into this country,” he said.

Redd testified to other successes over the past six years, saying authorities have taken thousands of terrorists off city streets and fields of battle and disrupted dozens of plots. He also said Washington is working more closely with many allies overseas and that authorities are clamping down on ways in which terrorists travel and raise money.