U.S. Homeland Security Secretary Tom Ridge called for stronger security for high-profile events scheduled to take place by the end of the year. Mr. Ridge announced plans to increase cooperation among U.S. agencies and private security organizations.

Mr. Ridge said that the key to the effort is better coordination among federal agencies such as the Department of Defense and Department of Energy, as well as individual states and the private sector.

"The homeland security is not about one department. It's not about one level of government, or just one organization," he said. "It is a national call to action, a philosophy of shared responsibility, shared accountability, and shared leadership."

Mr. Ridge said that we are entering a period "rich with symbolic opportunities for the terrorists," and he said potential targets include a World War II memorial that will be dedicated in Washington D.C. May 29 and the Group of Eight economic summit on Sea Island, Georgia, June 8-10. He added that U.S. Independence Day celebrations on July 4 provide other potential targets, as do political conventions for the Democrats in Boston and Republicans in New York later in the summer.

Mr. Ridge added the August Olympics in Athens, Greece, and Labor Day weekend celebrations throughout the United States in early September provide other possible targets for terrorist groups like al-Qaida.

Secretary Ridge outlined plans for a government task force to coordinate anti-terrorism efforts in remarks to the National Association of Broadcasters, now meeting in Las Vegas. A spokesman for the Department of Homeland Security described Mr. Ridge's comments as a "call to action."

The spokesman said that the plan is not a response to new information, but to analysis of continuing threats.

Mr. Ridge added that his department will work with seven other cabinet agencies to protect the national infrastructure, including rail lines, the electrical grid and 300 chemical sites.