WASHINGTON – The United States will keep its terror alert on high for mass transit as British officials try to determine the culprits and methods used in the London bus and rail bombings, Homeland Security Secretary Michael Chertoff (search) said Sunday.
Chertoff said the code orange alert for mass transit would remain at least through Monday while the U.S. government monitors the British investigation for information about who was responsible and "what kinds of tactics we have to worry about."
After four bombs exploded Thursday throughout the London subway and bus system, the U.S. raised its terror alert amid concern about a possible copycat attack.
Code orange indicates a high risk of attack, and in the U.S. system is the second-highest terror alert behind red. The lowest level is green, followed by blue and then yellow. Chertoff is considering changing the system amid complaints that it is to vague and confuses the public.
"I'd love to say we're going to see green in our lifetime," Chertoff told NBC's "Meet the Press." "It's kind of an aspirational state, but I can't tell you in the foreseeable future we're going to be below yellow."
In a round of interviews on Sunday talk shows, Chertoff and White House homeland security adviser Fran Townsend (search) said people in the U.S. traveling by rail and bus face risks of an attack similar to London's despite security improvements in recent years.
Townsend said authorities have improved mass transit safety since Sept. 11, 2001. "But there are no guarantees in this world," she said on "FOX News Sunday."
Chertoff said authorities can try to prevent a mass transit attack with intelligence and bomb detectors and plan to respond effectively if something happens. But he added that they can't eliminate the danger. "There is no perfect security in life," Chertoff said on ABC's "This Week."
While both Townsend and Chertoff said the U.S. is gathering intelligence to prevent an attack, both acknowledged that the government had no warning that the London system was going to be hit Thursday.
Townsend said the counterterrorism legislation that passed after the Sept. 11 attacks helps authorities gather intelligence to prevent attacks, and she argued that the war in Iraq is keeping terrorists off U.S. public transportation.
"If we're waiting until the very last second, where an individual is going to strap on a bomb on or plant a bomb in a subway system, we've waited until a point where we're least likely to be successful to prevent it," she said. "That's why you fight them away. That's why you're in Iraq and Afghanistan, fighting them there so you don't have to fight them here."