Members of the US Secret Service stand on Pennsylvania Avenue beside a barricade with new signs that read 'Police Line Do Not Cross', outside the White House in Washington D.C., USA. (Michael Reynolds/EPA)

AN INTRUDER makes his way deep inside the heavily guarded White House. In an earlier incident, shots from a high-powered rifle strike the president’s residence but are overlooked until a cleaning lady discovers the bullets days later. That such seemingly far-fetched scenarios weren’t lifted from a Hollywood script raises unsettling questions about the protection of the president and his family. These concerns urgently need to be addressed — but in a way that deals with real issues rather than just creating unsightly new barriers, further isolating 1600 Pennsylvania Ave. or pushing the public away.

A House committee will hold a hearing Tuesday on security breaches at the White House. It had been called after the Sept. 19 incident in which a troubled war veteran jumped the White House fence, ran across the lawn and entered through an unlocked door on the North Portico before being stopped by the Secret Service. Now it turns out there’s plenty more to discuss.

A report over the weekend by The Post’s Carol D. Leonnig detailed a string of lapses by the Secret Service in identifying and properly investigating a November 2011 attack on the White House. The seven shots were first judged to be harmless backfire from a construction vehicle and then assumed (incorrectly) to come from rival gangs. It became clear that the White House was the target and had been hit only when a housekeeper noticed the damage four days later. The incident is said to have angered President Obama and first lady Michelle Obama, who were not at the White House at the time but whose younger daughter and Ms. Obama’s mother were.

Neither the difficulty nor the danger of the job entrusted to the Secret Service can be minimized. But what does it say about the competence of the agency that a fence-jumper could get inside the White House and, as The Post reported Monday, far into the building before being tackled? What does it say about the culture of the agency that officers who realized gunfire had hit the White House were largely ignored and, it seems, afraid to speak up for fear of angering their bosses?

In the aftermath of the fence-jumping incident, three-foot-high barricades, posted with “Police Line Do Not Cross” signs, have been erected to keep people away from the fence. The Secret Service has floated the idea of shutting Pennsylvania Avenue to pedestrian traffic or setting up military-style checkpoints. No checkpoints can compensate if the agency doesn’t properly do its job. Conversely, a professional Secret Service should not have to maroon the White House on a defended, deserted island inside the nation’s capital.