CLEVELAND, OHIO (AFP) - Cleveland deployed overwhelming security on Sunday (July 17), bracing for possible violent protests as delegates poured into town for the Republican National Convention that will anoint Donald Trump the party's US presidential nominee.
The killing of three police officers on Sunday in Baton Rouge, Louisiana, only added to the tensions in Cleveland, where law enforcement agencies have thrown a ring of steel around downtown.
Authorities in the city on the shores of Lake Erie have erected 2.5-metre-tall metal fencing around the Quicken Loans Arena, closed off streets and deployed thousands of armed police officers.
The four-day political jamboree, which kicks off Monday, will see the bombastic billionaire secure the nomination for the Party of Lincoln after a thumping primary victory that confounded the US establishment.
Roads in the Ohio city are lined with concrete barriers and helicopters patrol overhead, as light aircraft, paid for by sponsors, trail anti-Hillary Clinton slogans.
Law enforcement is on edge, braced for protests from demonstrators enraged by Trump's divisive presidential campaign and preparing for the worst after anti-police violence erupted in Louisiana.
At least three officers were shot dead and three others were wounded in Baton Rouge, one of America's most racially segregated cities, which has seen days of protests against the treatment of blacks by law enforcement. The motivation for the latest shooting was not immediately clear, however.
Cleveland, a Midwestern city of nearly 400,000, has taken out US$50 million (S$67 million) in protest insurance, and Ohio's open-carry law, allowing people with proper permits to carry a loaded weapon on the streets, has inflamed fears of violence.
"We have policies in place for mass arrests through our prosecutor's office, our clerk's office and our court system," Cleveland police chief Calvin Williams told a news conference.
Williams said barricades had also been erected downtown to thwart any potential terror attack after a truck bomber killed 84 people in the French city of Nice last Thursday.
"We use blocking vehicles, we use concrete barriers and things like that at positions that we think may be vulnerable to attacks like that which happened in Nice," he said.
Trump, a New York tycoon who has never held elected office and who opposed the 2003 invasion of Iraq, vowed in his latest interview to wage war against the so-called Islamic State (ISIS) extremist group.
"We're going to declare war against ISIS. We have to wipe out ISIS," he told CBS in excerpts aired on the eve of the convention, which will culminate with a Trump speech accepting the nomination on Thursday.
"I am going to have very few troops on the ground. We're going to have unbelievable intelligence, which we need, which, right now, we don't have. We don't have the people over there," said Trump.
US Special Forces are already operating on the ground against ISIS, backed by US-led air strikes.
Trump made the remarks in his first joint interview with his pick for vice-president, Indiana's conservative governor Mike Pence, an evangelical Catholic.
Trump's choice of Pence, announced on Friday, has been
welcomed by 61 per cent of Republicans and conservatives in critical battlegrounds, states likely to decide the November election, according to a CBS News poll.
The survey found that these voters believe Pence brings stability to the ticket and will boost Trump's chances of defeating Clinton. Pence, however, is not well known beyond the party rank and file.
National polls show Trump tied with Clinton, who was branded "extremely careless" by the FBI in handling classified material in a long-running e-mail scandal dating from her time as secretary of state.
But Trump faces a herculean task to win over legions of critics.
His salty rhetoric and populist message have outraged many conservatives, raising fears he has fanned a racial backlash and prompting a battle for the soul of the Republican Party.
Unusually, the Cleveland convention features no former presidents, few party luminaries and only a smattering of elected officials. Instead it is expected to hand a starring role to Trump's family to make his case.
The first major anti-Trump protest was to kick off at around 4.00pm on Sunday (4am on Monday Singapore time), advertised as a "march against racism, Islamophobia, attacks on immigrants and on LGBTQ people and endless war" and was expected to draw 1,000 people or more.
Another "Stop Trump" march has been permitted by the city for noon on Monday, just hours before the convention launch.
The US homeland security secretary, Jeh Johnson, told Congress last week that he was concerned about demonstrations getting out of hand.
US authorities have been on alert since a gunman intent on killing white policemen went on a rampage and shot five Dallas officers dead earlier this month.
US political conventions, quadrennial affairs, are designed to bring a party together, formally select its presidential nominee and catapult the candidate and party towards November's election.