U.S. government officials, members of Congress and terrorism experts say Americans should brace for a long struggle against al-Qaida in the wake of Friday's failed bomb attack on a U.S. jetliner that landed safely in Detroit, Michigan.
The latest on the investigation into the foiled terror attack came from President Barack Obama, who is continuing his vacation in Hawaii.
The president told reporters that a preliminary review of what went wrong in the airliner incident should be completed by Thursday. But Mr. Obama said it is already clear that what he called a "totally unacceptable" systemic failure had allowed the bombing attempt to take place.
"What already is apparent is that there was a mix of human and systemic failures that contributed to this potential catastrophic breach of security. We need to learn from this episode and act quickly to fix the flaws in our system because our security is at stake and lives are at stake," he said.
Friday's incident aboard a U.S. airliner has served as a reminder about the threat of terrorism - more than eight years after the 2001 terrorist attacks on the United States.
That theme played out on the nation's airwaves Tuesday as lawmakers and experts warned of a long struggle ahead against terrorism in general and al-Qaida in particular.
Michigan Congressman Pete Hoekstra is the top Republican on the House of Representatives Select Committee on Intelligence. He spoke on CBS television's Early Show.
"The American people have to understand that this threat is real; it continues," he said. "It has been with us for almost 20 years and we need to be on offense. We need to be forward-leaning. We need to put in the latest technology. These folks are not going to go away."
New information has come to light about the suspect in the attempted bombing on the jetliner, Nigerian national Umar Farouk Abdulmutallab. Internet postings reported by various news outlets suggest that the 23-year-old Abdulmutallab was serious about his religious beliefs, and often was lonely and depressed.
Terrorism experts say that while the attack failed, Abdulmutallab's ability to get explosive materials onboard the aircraft raise serious questions about security procedures.
Former CIA analyst Michael Scheuer lectures on security studies at Georgetown University here in Washington.
"The fact is that we were badly beaten in this attack," he said. "The only thing that was missing, really, was the dead bodies. Everything else that al-Qaida would want out of the attack happened. Americans were terrorized, the expenses of air travel and protection for air travel are going up, and they have proved once again that they are a resilient enemy that we have not defeated or even come close to defeating yet."
At the same time, Scheuer says, the foiled attack also raises questions about the alleged terrorist.
"The plot and whatever training this gentleman got probably did come from Yemen and al-Qaida. But it clearly was not a professional job. This was not their 'A' team," he said.
Abdulmutallab allegedly hid the explosive materials in his underwear. Security experts contend he might have been detected before he got on the flight through the use of advanced imaging equipment that is in limited use in airports because of cost and privacy concerns.
Tom Blank is a former high-ranking official with the U.S. Transportation Security Administration.
"We have got to get over some of the privacy concerns and figure out how to use this technology in a broader way," he said.
Abdulmutallab's name was included in a broad database of individuals who are suspected of having some link to terrorism. But he was not included on higher-profile watch lists that might have caught the attention of security screeners. That raises questions about communication among government agencies and among countries.
Stewart Baker served in the Department of Homeland Security during the Bush administration. He says intelligence and security officials need to do a better job of sharing information and acting on it.
"The lack of communication, the lack of use of good data about who is a potential terrorist to decide what kind of screening they get," he said.
Abdulmutallab had a valid U.S. visa, even though his father had expressed concerns to U.S. Embassy officials in Nigeria several weeks ago that his son was being radicalized.
Former Homeland Security Secretary Michael Chertoff says that will be an area of focus as the investigation moves ahead.
"These visas that are sometimes given a year or two ago, and somebody gets radicalized in the intervening time, and it's important to make sure we go back and take a second look at those. And I think that is going to be an issue that they will be focusing on in the next five or six weeks," he said.
Counterterrorism experts say that last week's airliner incident serves as a stark reminder that the United States remains engaged in a long term struggle with terrorists who are determined to attack U.S. targets.
Juan Zarate was involved with anti-terror efforts with the National Security Council and the Treasury Department during the Bush administration.
"Thankfully, it was not a successful attack. But unfortunately, it portends a world in which we have got to look beyond a single theater and realize as we have said all along over the past eight years that we have got a global battle on our hands and an enemy that is able to adapt pretty easily," he said.
An al-Qaida affiliated group in Yemen claims that Abdulmutallab carried out the attack on their behalf. That claim has not been independently confirmed.
In his statement on Monday, President Obama said the U.S. will dismantle and defeat terrorists anywhere who might want to attack the United States.