President Bush has signed into law new measures to better prevent and respond to potential biological, chemical, or nuclear attacks against the United States.

The new Project BioShield authorizes $5.6 billion in spending during the next 10 years to develop cutting edge defenses against catastrophic attacks. President Bush says it is an important element of the fight against terrorism.

"On September the 11th, 2001, America saw the destruction and grief terrorists could inflict with commercial airlines turned into weapons of mass murder," he said. "Those attacks revealed the depth of our enemies' determination, but not the extent of their ambitions. We know that the terrorists seek an even deadlier technology. And if they acquire chemical, biological, or nuclear weapons, we have no doubt they will use them to cause even greater harm."

The new law directs government agencies to purchase 75 million doses of an improved anthrax vaccine for the strategic national stockpile. It approves spending for a safer, second-generation smallpox vaccine, an antidote to botulinum toxin, and better treatments for exposure to chemical and radiological weapons, including a children's version of an anti-radiation pill.

Mr. Bush says the law gives U.S. officials new authority to speed the research and development of the most promising medicines to protect against bioterrorism.

"We refuse to remain idle while modern technology might be turned against us," he said. "We will rally the great promise of American science and innovation to confront the greatest danger of our time."

The bipartisan legislation won near-unanimous approval in both houses of Congress. Surrounded by legislators in the White House Rose Garden, the president signed the bill into law at a desk with a sign that read: Protecting America.

Mr. Bush says Project BioShield is part of a broader strategy to defend against weapons of mass destruction. The government has already put in place advanced environmental detectors to warn of such an attack and has stockpiled enough smallpox vaccine for every American.