It's the weapon of choice of terrorists - the IED, an acronym that has crept into the vocabulary of Americans with the war in Iraq.
Yesterday, U.S. Secretary of Homeland Security Michael Chertoff came to Philadelphia to tout the ways the federal government was trying to raise understanding of "improvised explosive devices" - how they are made, who is using them, where and how.
Speaking to an audience of federal agents, bomb-squad officers and first responders outside City Hall, Chertoff said IEDs were a real and severe threat to cities like Philadelphia.
"The threat of IEDs is going to be with us for a long time," Chertoff said. "We have to stay ahead of it."
He said his department was making it a priority to analyze bomb attacks around the world and to share what it learned about enemy tactics with bomb squads and first responders across the country.
"The only way to defeat an IED attack is to be able detect it, prevent it and disarm it," Chertoff said.
He noted that an attempted bomb attack in London this summer was averted after an ambulance driver noticed something suspicious about a parked car.
At his stop in Philadelphia, Chertoff was joined by Mayor Street, Police Commissioner Sylvester M. Johnson, and Fire Commissioner Lloyd Ayers. After Sept. 11 and Hurricane Katrina, Street has made improving the city's emergency preparedness a priority.
He told Chertoff he was "grateful" for money that the federal government had given Philadelphia to improve its readiness but later added that it wasn't enough.
The Philadelphia region, including the surrounding suburbs, is receiving $18 million in grants from the Department of Homeland Security this year.
"We've got a huge communication issue we're trying to resolve," Street said.
If a bomb went off inside the city's transit tunnels, first responders would not be able to communicate. To fix the problem would cost about $30 million, Street said.
Today, homeland security officials will conduct an eight-hour training session on IEDs for first responders from the city and the surrounding region.
A centerpiece of that effort is an online service - called "TRIPwire" - that allows police departments and bomb squads to access intelligence about IED attacks.
The analysis includes everything from manuals on bomb-making, postings from terrorist Web sites, materials, even recipes.
Officer J. Graber, a member of Philadelphia's bomb squad, said specialists like him have relied on intelligence on bomb-making trends from soldiers returning from the war. The information, he added, could take a year or more to filter down to bomb squads in the field.
He said the federal government's new service would give squads better information more quickly.
In Philadelphia, the heightened awareness about bombs has led to a greater number of calls to the bomb squad about suspicious packages or situations. "We want people to notify us," said Capt. Walt Smith, head of the Police Department's antiterrorism unit.
One of the most recent verified threats was a pipe bomb that was deactivated in 2005 outside the southwest corner of City Hall.
MaryAnn Marrocolo, Philadelphia's head of emergency planning, said keeping on top of the trends in bomb-making was critical. "It's really important to understand what to look for in the case of IED," Marrocolo said. "They can be small devices that can be easily concealed. This kind of preventive course may allow officers to detect a device in advance of it going off, which can save lives."Contact staff writer Jennifer Lin at 215-854-5659 or email@example.com.