WASHINGTON – Homeland Security (search) officials issued a bulletin advising state officials, police and transit and rail agencies to be vigilant in light of the bombings in Spain.
They were asked late Thursday night to consider additional surveillance and to look out for unattended bags and backpacks, Homeland Security spokesman Brian Roehrkasse said.
Homeland Security officials were keeping close watch on developments related to the terrorist attacks that killed or wounded about 1,400 train riders in Spain.
Based on the current assessment of intelligence "we have no specific indications that terrorists are considering such attacks on the United States in the near term," Roehrkasse said Friday.
The attacks on Thursday have not prompted the United States to raise its terror alert level, which remains at yellow, indicating an "elevated" threat.
Amtrak increased patrols of its police force and canine units, spokesman Dan Stessel said. Electronic surveillance of bridges and tunnels was intensified, he said. And the company reinforced its message to Amtrak (search) employees to report suspicious activities to police.
"That gives you another 20,000 sets of eyes," Stessel said. The railroad is continuing to review information received from the FBI and the Transportation Security Administration (search), he said, but there has been no credible threat against Amtrak or other railroads.
Acting TSA chief David Stone said the agency has been working with public transit systems to close security gaps.
"TSA is very much involved in all risk mitigation plans with trains, metropolitan transit systems and ports," he said.
In New York, Mayor Michael Bloomberg said authorities had moved to increase security in city subways and commuter trains. Uniformed personnel will be present at subway stations and trains, on the Long Island Rail Road, PATH and Metro-North Rail Road trains. Bomb sniffing dogs will also be in use around the region.
"We clearly are focusing, as you would expect us to do, even more resources on the New York City subway system," Bloomberg said at a news conference. "It goes to show we still live in a very dangerous world."
Bruce Hoffman, a terrorism expert at the Rand Corp., said it's much harder to secure transit systems than airports because it isn't possible to closely scrutinize every person in such large crowds.
"If terrorists want to kill a lot of people, public transportation is always the preferred target, because you get a lot of people in the same place at the same time," he said.
Though airplanes continue to be an attractive target for terrorists, he said, the U.S. government's tightening of airport security may have made public transit more vulnerable.
"You harden one target and you shift the threat to another," Hoffman said.
Further, he said, the success of the attacks on trains in Madrid may inspire other terrorists to imitate them.
If the TSA gets wind of a threat, the agency's communication system allows it to communicate quickly with transit agencies, railroads, bus companies and cruise lines, officials said. The agency has given $115 million in security grants to transit systems in the past year.
James Carafano, a homeland security expert with the conservative think tank Heritage Foundation, said Al Qaeda has shown an interest in bridges and tunnels. Major subway systems are now closely monitoring tunnels, he said.
"The major subway systems are better prepared than they were several years ago, and that's encouraging," Carafano said.
The Federal Transit Administration has sent technical teams to transit systems to assess their vulnerability and given them grants for training their employees.
In Washington, metro subway platforms were cleared of fixtures that officials thought could be hiding places for bombs. Officials removed trash cans, newspaper recycling bins and newspaper sales boxes.
Mailboxes disappeared from downtown Washington streets as the city tightened its guard against terrorism.
Last month, Homeland Security officials met with a Russian delegation for a debriefing on the February explosion on the Moscow metro that killed 41, TSA spokesman Mark Hatfield said.
"You can bet we're going to be talking to our allies in Spain and try to boil down lessons learned as the investigation into this horrible attack take place," he said.