Obama's guards under fire

Barack and Michelle Obama rely on the Secret Service to keep them safe but recent incidents have shaken that faith. Picture / AP

Secret Service faces grilling after recent string of security failures

A knife-wielding intruder allowed to run rampant through the first floor of the White House. Bullets that struck the window of Barack Obama's private residence but went unnoticed for days. A presidential bodyguard so drunk he passed out in a hotel.

These are just some of the recent incidents that have shaken confidence in the Secret Service, the elite agency assigned to protect Obama and his family.

Today Julia Pierson, the Secret Service's director, will face a grilling from members of Congress and has a battle to convince them that her agents are up to the task of protecting the world's most powerful man.

The hearing was called after a September 19 incident, when the Secret Service allowed Omar Gonzales, a troubled Iraq war veteran, to scale the White House fence and go through the unlocked front door of the executive mansion.

Gonzales, who was carrying a knife in his pocket, was apparently intent on warning Obama that "the atmosphere was collapsing".

Footage shows him limping across the White House's north lawn, unchallenged by agents on the ground or the sharpshooters on the roof.

He then burst past a guard and ran through the White House's first floor before finally being tackled in the East Room, where Obama often gives speeches and press conferences, according to the Washington Post.

But members of Congress will have questions about the Secret Service's competence beyond that incident.

Gonzales was arrested in July with 11 guns in his car, including high-power rifles with scopes, and a map on which he had drawn a line to the White House. He was let free but weeks later was stopped outside the White House with a hatchet inside his trousers. Again, he was let go.

His breach of the White House's elaborate security perimeter is just the latest in a series of mistakes made by an agency that prides itself on silent professionalism.

Obama is said to face an unprecedented level of death threats - both from right-wing extremists and Islamist militants - and the misfires by the Secret Service have dented the agency's projection of invincibility.

Publicly, the White House insists it still has faith in the President's phalanx of bodyguards.

"Their task is incredible, and the burden that they bear is incredible," said Tony Blinken, a senior presidential aide. "The Secret Service is investigating this and they will take any steps necessary to correct any deficiency."