‘It was unacceptable’: Secret Service head breaks silence after Trump shooting as questions swirl over how it unfolded

The head the Secret Service has admitted that it was «unacceptable» for an armed assassin to come so close to killing former president Donald Trump.

In her first public comments since Saturday's shooting, USSS director Kimberly Cheatle said the gunman should never have been allowed to get in a position to take his shot and that «the buck stops with [her]».

«It was unacceptable, and it's something that shouldn't happen again,» Cheatle said in an interview with ABC News on Monday.

«It was obviously a situation that as a Secret Service agent, no one ever wants to occur in their career. The buck stops with me… and I need to make sure that we are performing a review and that we are giving resources to our personnel as necessary.»

However, Cheatle said she would not resign from the role despite questions about the Secret Service’s preparation and handling of the rally.

She also repeated that the assassin's perch was outside the area that had been secured by her agents, with responsibility instead falling to the local police department.

Questions, criticisms, and conspiracy theories have swirled around the USSS ever since 20-year-old Thomas Matthew Crooks crawled up onto a roof less than 150 meters away from Trump's podium and opened fire with a semi-automatic rifle.

Witnesses claim that they tried to warn law enforcement agents about a suspicious man on the roof several minutes beforehand, and police did see signs of trouble. The USSS also had counter-sniper teams on the scene whose task was to watch for and respond to long-range threats.

Officials have said that a local police officer did attempt to climb onto the roof and investigate, but was forced to let go and drop painfully to the ground when Crooks swung his weapon