In a July 29, 2009, speech in New York, Department of Homeland Security Secretary Janet Napolitano said, "While the terror threat is ever-changing, it is critical to reiterate that the threat remains. The consensus view of the intelligence community, of which DHS is a member, is that the terror threat to the homeland is, quote, 'persistent and evolving.'
"The threat of a nuclear or radiological device is of grave concern, and reducing that threat is a key administration priority. But we must be equally prepared for biological or chemical threats, which are capacities al Qaeda has sought for years." Napolitano said.
While the United States has made substantial efforts to harden borders by preventing potential terrorists and individuals on watch lists from gaining entry into the United States, the issue of illegal migration and border crossings continues to be a substantial threat.
In her July speech before the Council on Foreign Relations, Napolitano said, "We are also keenly aware that illegal immigration is not only a matter of sovereignty but could pose a national security threat, as well. The reality that potential terrorists could use a variety of ways to enter the country illegally -- fake documents, visa overstays and even border tunnels -- make this so."
In July, former members of the 9/11 commission, after meeting with Napolitano, estimated that about 80 percent of their recommendations issued five years ago had been fully enacted.
Contacted on Thursday, former 9/11 commissioner Fred Fielding, who was also White House counsel under President Bush in his second term, said, "We are safer ... but we are not there yet."
While DHS has established the US-Visit Program to gather biometric fingerprints and pictures of non-U.S. citizens entering the United States, the monitoring of who has been leaving the country is something that has not been handled effectively, according to some intelligence analysts.
Former 9/11 commission co-chairman Lee Hamilton said July 24, 2009, after meeting with Napolitano, "There has been quite a bit of progress ... that has been made with regard to entry. The exit problem, so far as I know, has not really been addressed at this point, and that will be a challenge for the department."
The United States has developed and maintained huge databases to assist and detect any nexus to terrorism ranging from the terror watchlist to shipping manifests.
In 2006, then-DHS Secretary Michael Chertoff oversaw efforts to have the United States receive significant amounts of airline passenger data (passenger name records) in efforts to screen for potential terrorists who may not be on various watchlists maintained by U.S. law enforcement and intelligence agencies.
Passenger data includes information in more than 30 fields, including reservation information, who booked the flight, payment methods and telephone information provided as part of the reservation booking. Passenger data is more thorough than flight manifests, which DHS officials use to check against terrorism watchlists.
The continuing vulnerabilities in port security is one area that counterterrorism experts and U.S. officials have expressed concern about. DHS has set up several key programs over the past few years, such as the Container Security Initiative and the Customs-Trade Partnership Against Terrorism plan, which increases information sharing with shippers.