US police plan ring of steel around Democrats' convention

Possible threats at event range from violent protests to lone-wolf revenge attacks

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As Chicago welcomes Democrats for their national convention on Aug 19, security services are bracing themselves for an array of possible threats from potentially violent protests to lone-wolf bids to avenge the attempt on Donald Trump's life.

The third-largest US city has been hosting political party gatherings dating back to the nomination of former president Abraham Lincoln in 1860, and law enforcement agencies are determined that its 26th national convention will be among the most secure.

More than 50,000 activists are expected to flock to downtown Chicago from Aug 19 for the fourday bonanza, set to be a festive celebration of the Democratic Party's new standard-bearer, Vice-President Kamala Harris.

High-profile participants - from musicians and Hollywood stars to President Joe Biden - are expected, and the Secret Service, Federal Bureau of Investigation (FBI) and local police have spent a year planning an ironclad security cordon around the downtown United Centre arena.

Mr Lucas Rothaar, the FBI's top special agent in Chicago, told journalists at a briefing that there were no specific concerns but warned of an "elevated threat environment".