Secret Service sets up 'Fortress Trump' with snipers on rooftops as Republican returns to scene of assassination attempt in Butler, Pennsylvania

The U.S. Secret Service erected a ring of steel around Donald Trump as he returns to the scene of a failed assassination attempt 12 weeks ago.

As thousands of supporters poured into the grounds of the Butler Farm Show in Pennsylvania snipers sat atop cargo containers and agents swarmed the area along with police on horseback, turning it into a security fortress.

On July 13, gunman Thomas Crooks fired a hail of bullets from the roof of a nearby glass company warehouse which had, disastrously, been left unguarded, hitting Trump in the ear.

For Trump's return a sniper was positioned on the warehouse roof many hours before his arrival and roads leading to the building were sealed off by local police. This time it will be inside the event's security perimeter.

On the stage a bullet proof screen was set up around the front and both sides of the lectern Trump was due to speak from.

A line of cargo containers was also placed on an area of grass between the stage and the warehouse, also blocking other buildings with possible lines of sight to the podium, including a water tower.

In the bleachers behind the stage had been placed the firefighter uniform of Corey Comperatore, who was killed in the attack.

The massive security operation has been planned for two weeks and involves counter sniper teams, counter assault teams and technology to repel drones.

U.S. Secret Service spokesperson Anthony Guglielmi said: 'Since the attempted assassination of former President Trump on July 13, the U.S. Secret Service has made comprehensive changes and enhancements to our communications capabilities, resourcing, and protective operations.

'Today, the former President is receiving heightened protection and we take the responsibility to ensure his safety and security very seriously.'

TSA agents were operating metal detectors at the entrance and agents from the Department of Homeland Security's Homeland Security Investigations were inside and outside the venue.

It came amid ongoing Iranian threats against Trump.

The Department of Justice said it is 'intensely tracking Iranian lethal plotting efforts targeting former and current U.S. government officials, and that includes the former president.'

Local Republican congressman Mike Kelly said: 'We started from square one, including the perimeter. It’s going to be way outside, with the AGR Building (the warehouse where Crooks shot from) within that protected area.

'The water tower will be protected. We have a shield around the outside, more or less, that will protect that area and the people that are there.

'The AGR property will be totally roped off, nobody allowed on there. We’ll make sure it’s safe.'

Speaking last week Trump said: 'I really believe that will be the safest place on Earth.'

But the assassination attempt, in which his ear was grazed by a bullet, has reshaped how he campaigns.

There have been death threats directed at his aides, and his team isn't as able to quickly organize the mass rallies that have always been the signature of his campaigns.

Events have been canceled and moved around because the Secret Service lacked the resources to safely secure them.

Even with the use of glass barricades to protect Trump onstage, there are concerns about holding additional rallies outdoors due to fears about drones.

Trump campaign senior adviser Chris LaCivita said: 'If there's one group of people that can handle something like this thrown in their lap, it's the team that Donald Trump assembled to run this campaign, just based on everything we've had to deal with, whether it's lawsuits to keep him off the ballot, to indictments, to assassination attempts.'