CHICAGO (CBS) — Mayor Emanuel acknowledges Chicago could be a target for terrorism as air strikes against Islamic State militants in Iraq and Syria continue, reports WBBM Political Editor Craig Dellimore.

Mayor Emanuel says the quick response to a suspicious package left at O’Hare Airport shows that the city is taking the threat of possible terrorism here seriously. He says it shows the city does have a plan in place, and is working closely with the federal government.

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The mayor says Chicago has an advantage because of its Emergency Management and Communications system to coordinate as well as communication with federal law enforcement.

“We’re working constantly at a local level with our federal partners, whether that is the FBI or national security in coordinating safety, security throughout the city,” he said.

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The mayor says he’s thankful that the incident at the airport turned out to be nothing.

CBS 2’s Jim Williams reports while it was a false alarm at O’Hare, a recent post on Twitter said ISIS was already in Chicago. And the terrorist publication Inspire has made several references to the city.

Are those phony threats? The head of the FBI’s Chicago office is taking them seriously.

“I can’t sit here and tell you that there’s an imminent threat, but we are very, very concerned on the homegrown violent extremists that are still here in the United States and certainly the ones that are attempting to travel overseas,” said Chicago FBI Chief Robert Holley.

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The FBI chief here says agents are using every tool available to track down would-be terrorists and stop them before they strike.