As Americans celebrate Osama bin Laden’s demise, security agencies across the nation are amping up their vigilance in anticipation of an act of revenge by bin Laden’s associates.

In New York, law enforcement is watching more closely high-value targets like airports, train stations, the Stock Exchange and the Empire State Building. Los Angeles, similarly, has increased security around airports and other potential targets.

Given the circumstances, heightened security measures are to be expected. After all, warns the Department of Homeland Security, al Qaeda “may seek to accelerate plotting efforts in the homeland.”

But what’s needed here are prudent, measured responses. Over-reaction — including knee-jerk reactions to unspecific threats — would be wasteful as well as unhelpful.

Since 9/11, the United States has foiled at least 38 plots by Islamists intent on wreaking terror in our homeland. Twenty-nine of those plots were foiled by nothing more — and nothing less — than good police work. This shows that the right way to prevent terrorism is through effective law enforcement cooperation — not by trying to terrorist-proof every potential target in the nation.

Unfortunately, political leaders, fearful of looking lax on security, have fallen prey to wasteful and unworkable security initiatives that look pretty on paper — but spend billions of taxpayer dollars without tangible security benefits.

One example: the recently scrapped Homeland Security Advisory System. The “color-coded” system was useless. For starters, few people could tell the difference between a yellow or orange alert; these were distinctions without a meaningful difference. Vagueness is no virtue in any “advisory system.”

Also problematic: Citizens had no way to understand how various colored threats might affect their local communities. An elevated threat level in New York might mean little to citizens in Los Angeles . . . or it might mean a lot. No one ever knew.

Thankfully, the new system focuses on ensuring that alerts are clear and specific. Secretary Napolitano should be applauded for choosing not to increase the terror threat level after bin Laden’s death, explaining that she lacked evidence of any specific plot. This will help ensure that Americans will take future alerts seriously and not simply cast them off as another instance of DHS crying wolf.

Bin Laden’s death is an opportunity for the U.S. to refocus on what has worked since 9/11. The 38 plots show that homeland security requires the effective integration of federal, state, and local efforts, as well as cooperation from the private sector, individual citizens and allies abroad. Time and again, tools like the PATRIOT Act and robust relationships between the U.S. and its allies have proved vital in disrupting plots.

Bin Laden’s death is demoralizing for al Qaeda and will likely weaken its capabilities. But it will not be in the end of al Qaeda. Al Qaeda in the Arabian Peninsula — only one of many al Qaeda offshoots — has tried to attack the U.S. multiple times in the last few years and can be expected to continue these efforts. Bin Laden may be gone, but the War on Terror is far from over.

It makes little difference whether an act of terror is plotted in retaliation for bin Laden’s death, or as a perverse expression of piety by a lone wolf, homegrown Islamist. Staying diligent and using the lessons of the past 10 years to guide counterterrorism policies can help us to prevent the next attack.

Jena Baker McNeill is The Heritage Foundation’s senior policy analyst for homeland security.