Chicago has become one of the top targets of international terrorists over the past six years, said a top security expert after considering threats by Islamic State militants on Twitter.
According to CBS, the threat post by IS militants on Twitter showed the Old Republic Building and 307 North Michigan Avenue in Chicago.
The Twitter post said that the IS militants were already present in US cities and streets.
The post also claimed that the US would always remain the top target of IS militants.
A security expert said that the death of Osama Bin Laden and U.S. airstrikes to weaken terror networks could be the reasons behind the threat.
He added that Chicago was referred as 'Obama town' among terrorists.
