Wall St. Journal:

    Americans went to work yesterday to news of another astonishing terror plot against U.S. airlines, only this time the response was grateful relief. British authorities had busted the "very sophisticated" plan "to commit mass murder" and arrested 20-plus British-Pakistani suspects.

    ...the diabolical scheme was to smuggle innocent-looking liquid explosive components and detonators onto planes. They could then be assembled onboard and exploded, perhaps over cities for maximum horror. Multiply the passenger load of a 747 by, say, 10 airliners, and this attack could have killed more people than 9/11. We don't yet know how the plot was foiled, but surely part of the explanation was crack surveillance work by British authorities.

    British antiterrorism chief Peter Clarke said at a news conference that the plot was foiled because "a large number of people" had been under surveillance, with police monitoring "spending, travel and communications."

    Let's emphasize that again: The plot was foiled because a large number of people were under surveillance concerning their spending, travel and communications. Which leads us to wonder if Scotland Yard would have succeeded if the ACLU or the New York Times had first learned the details of such surveillance programs.

    Democrats and their media allies screamed bloody murder last year when it was leaked that the government was monitoring some communications outside the context of a law known as the Foreign Intelligence Surveillance Act.

    This year the attempt to paint Bush Administration policies as a clear and present danger to civil liberties continued when USA Today hyped a story on how some U.S. phone companies were keeping call logs.

    And then there was the recent brouhaha when the New York Times decided news of a secret, successful and entirely legal program to monitor bank transfers between bad guys was somehow in the "public interest" to expose.

    For that matter, we don't recall most advocates of a narrowly "focused" war on terror having many kind words for the Patriot Act, which broke down what in the 1990s was a crippling "wall" of separation between our own intelligence and law-enforcement agencies.

    There is also continued angst about the detention of terror suspects at Guantanamo Bay, even as Senators and self-styled civil libertarians fight Bush Administration attempts to process them through military tribunals that won't compromise sources and methods.

    The real lesson of yesterday's antiterror success in Britain is that the threat remains potent, and that the U.S. government needs to be using every legal tool to defeat it. At home, that includes intelligence and surveillance and data-mining, and abroad it means all of those as well as an aggressive military plan to disrupt and kill terrorists where they live so they are constantly on defense rather than plotting to blow up U.S.-bound airliners.