Cleveland - A ring of steel will descend next week around the Republican National Convention, transforming Cleveland into a fortress as it prepares to welcome Donald Trump with political pomp and angry protests.Authorities overseeing and protecting national party conventions in the United States are always on high alert for disruption, or worse - they are dubbed National Special Security Events by the Department of Homeland Security, and federal agencies pour in resources to ensure a safe event.But extraordinary circumstances surround the July 18-21 Republican confab, where Trump is set to become the party's standard-bearer to face Democrat Hillary Clinton in the November election.It comes less than two weeks after a gunman bent on killing white policemen murdered five Dallas officers, and a month after 49 died in a nightclub massacre carried out by a man authorities said was radicalised by Islamist propaganda.As Cleveland prepared for the spotlight, a suspected terrorist attack on Thursday killed at least 84 people in Nice, France when a man drove a truck into a crowd at Bastille Day celebrations.Hostile takeover Trump dominated a divisive and unruly primary season, infuriating minority groups, antagonising many people within his own party, and drawing violence to his campaign rallies.His hostile takeover of the Republican Party may provoke a rough reception from some disgruntled delegates inside the convention hall. Trump critics outside could well prove chillier than the midwestern city's "lake effect" snow.Complicating matters, Ohio's open-carry laws mean the public will be legally allowed to bring their guns to convention events downtown, although not inside the hard security perimeter around the convention itself."We'll take care of what we need to take care of," Cleveland patrol officer Paul Fronckowiak told AFP.Several thousand officers from Ohio and beyond will be engaged in protecting the convention.FBI Director James Comey said his department had hundreds of personnel focused specifically on anti-terrorism intelligence gathering in Cleveland."Any time there is a national spotlight on a political event there is a risk that groups that aspire to do just that, to engage in acts of domestic terrorism, will be attracted," Comey testified on Thursday before the House Homeland Security Committee.DHS Secretary Jeh Johnson acknowledged demonstrations could get out of hand."I am concerned about the possibility of violence," he told lawmakers, adding that DHS is sending more than 1,000 agents to Cleveland, including Secret Service officers. Security experts have advised news organizations to bring protective gear like helmets, bullet-proof vests and gas masks.'Prepared for anything' The city showed off some of its security assets on Thursday, including horse-mounted officers and bomb disruption devices like the Andros-F6 robot."This is our workhorse," Fronckowiak said of the shiny grey front-line mobile bomb unit.The security curtain had yet to be fully draped over Cleveland by Thursday.The public had unencumbered access up to the front doors of The Q, as the arena is known. Inside, hundreds of contractors were scrambling to convert the champion Cleveland Cavaliers NBA basketball team's home court into the Republican Party's national stage.While thousands of segments of fencing were stacked along roadways in preparation for forming security perimeters, no armoured vehicles or riot police were yet in sight.But authorities have assured that they are ready for any contingency."We're prepared for anything and everything that will or won't happen," Police Chief Calvin Williams said.Protest groups plan to demonstrate over the weekend, including at a Sunday gathering described as a march against racism, Islamophobia and attacks on immigrants.On Monday, hours before the convention opens, Stand Together Against Trump expects thousands of people to march near The Q in a city-approved protest.Organizers expressed confidence their marches will be peaceful."This is an opportunity to come together," said Jana Hambley, a coordinator for the group and a surgery resident at a Cleveland hospital.That coming together may involve politically opposed protesters, anarchists or other troublemakers squeezed into close quarters, police said.White supremacist groups are expected to come to Cleveland, as are the Oath Keepers, current and former members of the military with a propensity to show up at events heavily armed.The open-carry gun laws have clearly heightened tensions."Is it a prescription for calamity or crisis? No one knows," Ryan Lenz, of the Southern Poverty Law Center which tracks extremist groups, said of the potentially combustible mix of protesters facing off and bearing arms."No one can say which way it's going to fall."