WITHOUT QUESTION, the new and so far low-profile homeland security secretary, Michael Chertoff, had the tone right yesterday. Without inspiring panic or a massive wave of duct-tape purchases, he announced that security would be raised on the nation's largest and most vulnerable transit systems -- Washington's Metro among them -- to help avert the possibility of copycat bombings. D.C. authorities spoke in the same spirit. "Live your lives, go to work," said Mayor Anthony A. Williams, emphasizing the lack of a specific threat to the Washington region. But he was followed by the chief of Metro transit police, Polly Hanson, who confirmed what Metro riders yesterday had already noticed: Extra police and security measures were put in place as soon as news broke of events in London. Both the rhetoric and the actions taken yesterday are signs that the nation's ability to react quickly to terrorist threats has matured and improved since Sept. 11, 2001.

But the attacks in London do call into question the Bush administration's priorities. This is the second major terrorist attack on a mass transit system in a large city. Yet most of U.S. transportation security resources are still focused on airplanes. Aviation security accounts for almost 90 percent of the $5.5 billion budget of the Transportation Security Administration, a body created to protect all transportation, not just airlines. Richard A. White, chief executive of Metro and chairman of the American Public Transportation Association, points out that while the federal government has spent $18 billion on aviation since Sept. 11, only $250 million has been spent on transit security. Given that public transit carries 16 times as many passengers every day, this proportion is clearly wrong.

Yet the District has been luckier than most: Metro has received some $55 million in federal money over the past three years. But Mr. White and his colleagues still say that two separate threat assessments, carried out by the Homeland Security and Transportation departments, showed that Metro should spend a further $143 million, mostly to build a backup control center. That money has not been forthcoming, either from local authorities or from the federal government. Given the amount of money being spent on other areas of homeland security, that is a mistake.

True, the most expensive security measures are not necessarily the only effective ones, especially where public transit is concerned. Training for rail and bus officials that teaches them how to recognize a suspect passenger, public education for subway riders that teaches them how to recognize a suspect package -- all of this may one day prove the best prevention of all. We maintain, as we wrote after the Madrid bombings, that the best thing Metro riders can do is to put down their newspapers occasionally and look around for odd behavior and suitcases that don't appear to belong to anyone. If it happened in London, it can happen here, too.