It's been three years since four hijacked planes crashed into the World Trade Center, the Pentagon and a field in Pennsylvania killing 3000 people. The response to the September 11, 2001 attacks has been an American-led global war on terrorism. The debate continues on whether any nation is winning that war.

The U.S. took the war against al-Qaida, masterminds of the 9/11 attacks to Afghanistan removing the Taleban which had given sanctuary to al-Qaida. It did not capture al-Qaida's leader, Osama bin Laden, but did capture or kill some of his deputies. That did not prevent major terrorist attacks in Bali, Riyadh and Madrid carried out by groups linked to al-Qaida.

Former New Jersey Governor Thomas Kean headed an exhaustive investigation by a Commission chartered by Congress to give a full and complete account of the September 11th attacks. The commission concluded that although al-Qaida no longer directs operations, it initiates and inspires.

"Because al-Qaida represents an ideology, not a finite group of people, we should not expect the danger to recede greatly in years to come," he said. "No matter whom we kill or capture, including Osama bin Laden, there will still be those who plot against us."

Congress acted quickly to endorse the 9/11 Commission recommendations, holding more than a dozen hearings during what is normally a summer recess. Legislation to adopt the recommendations, usually a slow process, is expected to be approved by the end of September because, as Republican Senator John McCain says the country is still at risk.

"International terrorism poses a real and present danger and it is our responsibility to take action on the commissions recommendations regardless of committee or party or jurisdiction or turf," he said.

The Bush administration also took the war on terror to Iraq arguing there was a link between Saddam Hussein and al-Qaida. On the American domestic front, the Department of Homeland Security has increased security at borders, airports, nuclear power plants and government facilities, and yet, three years later, Homeland Security Secretary Tom Ridge says, the challenge to prevent future terrorist attacks is daunting.

"Every day we must operate with the knowledge that our enemies are changing based on how we change. And as we shore up one vulnerability they're likely to look to uncover another," he said.

Neil Livingstone, a terrorism expert based in Washington, D.C. says terrorism is an open-ended war, "To say that we're winning suggest that there's going to be an absolute end to this struggle that we're involved in."

Mr. Livingstone says the nature of the war may change, as may the opponent. "Part of our problem today is there are other major terrorist centers, and we need to do something about those," he said. "Iran has been ever since 1979, 1980 really the wellspring of terrorism in the world and of Islamic fundamentalism."

Deputy Secretary of Defense Paul Wolfowitz says the global threat of terrorism demands a global response. "Victory in the war on terror requires sowing the seeds of hope and expanding the appeal of freedom, particularly in the broader Middle East and Muslim world," he said.

Secretary Wolfowitz says we'll never know how many attacks similar to 9/11 have been prevented. On the third anniversary of that attack, the war on terrorism continues.