The president says the London attacks provide a bloody reminder of the true nature of the terrorist threat.
"We will not let down our guard. And therefore, at home we are doing everything we can to protect the American people," said Mr. Bush.
He spoke during a visit to the port of Baltimore, Maryland, the closest major seaport to Washington, D.C. In a speech to port security workers, he said the government is continuing to pour resources into homeland security. He said in the war on terrorism, every effort must be made to protect the public.
"And so we'll continue to enhance protection at our borders and coastlines and airports and bridges and nuclear power plants and water treatment facilities, and other critical sites, including transportation infrastructure," he added.
Mr. Bush noted that since the September 11, 2001 attacks on the United States, Washington has allocated more than $350 million to improve security on mass transit systems across the country. He also stressed that major efforts have been made to improve safety at the nation's ports, and to unify the various agencies within the federal government that play a role in fighting terrorism.
The president said legislation passed by Congress after the September 11 attacks has given law enforcement agencies an enhanced ability to share information and track terror suspects. Provisions of the law, formally known as the Patriot Act, will expire later this year, and Mr. Bush pressed for congressional renewal.
"As we saw in London, the terrorists are still active and they are still plotting to take innocent life," he said. "So my message to the Congress is clear: This is no time to let our guard down, and no time to roll back good laws. The Patriot Act is expected to expire, but the terrorist threats will not expire."
The president and his Republican colleagues in Congress say the Patriot Act is a responsible, effective tool which enables law enforcement agents to track terrorists in the same way they investigate drug dealers and other criminals. But critics charge some aspects of the law infringe on individual rights, especially those dealing with telephone taps and searches. They also say the Bush administration has not provided sufficient funds to local governments to protect their mass transit systems.