Unprecedented Security Measures Taken at Capitol for Bush’s Speech : Terrorism: Police sharpshooters and a dynamite-sniffing device are all part of unusual precautions, amid fears of attacks on officials.

Amid fears of a terrorist attack, officials took unprecedented security precautions Tuesday as most of the government’s top officials and many foreign diplomats gathered in the House chamber to hear President Bush’s State of the Union speech.

Measures ranging from a dynamite-sniffing device to waves of police and rooftop sharpshooters gave Capitol Hill the look of a combat zone, reflecting tensions over the war in the Persian Gulf.

Security is usually tight for presidential inaugurations and State of the Union speeches but steps taken Tuesday were extraordinary. Police closed all streets within a four-block radius of the Capitol two hours before Bush arrived and subjected the news media, gallery spectators and congressional employees to unusually strict security checks.

Senators and representatives who planned to attend the speech were advised to use the Capitol complex’s underground tunnels as much as possible and to keep a low profile.

In a move with a long tradition but a special urgency this year, one Cabinet member was secretly told not to show up for the speech. The idea was to have someone in the line of succession to the presidency who would survive any potential catastrophe at the Capitol.

As Cabinet members filed into the House chamber right before Bush spoke, it became apparent that the “designated survivor” was Interior Secretary Manuel Lujan Jr. He was provided with a special security detail at an undisclosed location in the Washington area, sources said.

Rep. Vic Fazio (D-Sacramento), a House leader involved in security planning, said that the measures were prompted by “some intelligence input that the potential for state-sponsored terrorism is greater now than it has ever been because we are at war.”

He added that it is “not surprising that national monuments and assemblages of important officials would be among the major targets.”

Jack Russ, the House’s cautious sergeant-at-arms, reportedly told lawmakers at a recent briefing on the security measures: “The question is not whether or not we’ll have a terrorist attack on Capitol Hill, the question is when.”

The legislators were advised how to protect themselves and how to recognize letter bombs. They also were urged to change personalized license plates that list their state and district. For many lawmakers, that posed a sticky trade-off between prudence and privilege: the plates enable them to park almost any place in Washington.

Sen. John H. Chafee (R-R. I.) sheepishly acknowledged Tuesday that he forgot that he had changed his tag--and was ticketed in a no-parking zone at his health club.

Those entering the Capitol for the speech had to pass through two electronically operated security gates, one checking for metallic weapons (guns and knives), the other for dynamite. Machines that can detect plastic bombs are still being perfected. Several years ago, a man with plastic explosives strapped to his body was arrested in the House spectators’ gallery.

The metal detectors, the same as those used in airports, were installed all over Capitol Hill after the detonation of a bomb in 1983 outside the Senate chamber.

But the dynamite-sniffing device, provided by Ion Track Instruments of Wilmington, Mass., is a new wrinkle on the Hill, although it is currently being used at high-risk military and nuclear installations.

The device can detect the emission of special chemicals that are required to be implanted in dynamite as the result of a law passed by Congress several years ago.

Days off were canceled for all of the Capitol Police’s 1,400 officers, who fanned out over the 155 acres of Capitol park-like grounds, buildings and parking lots. The force is one of the largest per capita police forces in the nation--one officer per 15 inhabitants of Congress’ buildings. The District of Columbia police field about one officer for every 160 residents of Washington.

Television news crews who brought their cameras and lights into the Capitol for post-speech interviews of lawmakers had to go through unusually severe checks, according to Tina Tate, superintendent of the House Radio-TV Gallery.

“All the gear had to be swept and constantly attended,” she said.

Capitol security forces were linked by radio hookup with other law enforcement agencies, such as the Secret Service, and with key government agencies, including the State and Defense departments.

Fazio, who chairs the House subcommittee that handles legislative appropriations, said that he hopes the wartime security precautions will lead to permanent measures.

Fazio and others advocate placing a fence around the Capitol grounds and requiring visitors to enter through a limited number of gates, as they do at the White House.

Currently, visitors can roam the Capitol grounds freely, entering Congress through numerous doors. Critics of the fencing say that it would unnecessarily degrade the symbolic openness of the world’s prime seat of representative government.