Secret Service Director Promises Congress Security Fail 'Will Never Happen Again'

“All decisions made that evening are being evaluated, including decisions on tactics and use of force, in light of the totality of the circumstances confronting those officers,” she said.

Pierson noted that problems exist within the agency. She reported that 16 individuals have vaulted the White House fence over the past five years – six just in this past year. Only Gonzalez made it into the building.

“Let me also say that I recognize that these events did not occur in a vacuum,” she said. “The Secret Service has had its share of challenges in recent years – some during my tenure and some before – of which this is the most recent. I intend over the coming months to redouble my efforts, not only in response to this incident, but in general to bring the Secret Service to a level of performance that lives up to the vital mission we perform, the important individuals we protect and the American people we serve.”

The service, Pierson said, has actually upgraded White House security measures over the past five years including perimeter cameras, officer booths, vehicle access gates and command and control systems, along with enhancements to highly classified programs “that have made the president and complex more secure.”

“We remain dedicated and committed to protecting the president and first family and the sanctity of the White House complex within the bounds of the Constitution and laws of the United States,” she said.

But lawmakers were far from assured, noting that the initial reports regarding the Gonzalez incident indicated the intruder barely got through the door – actually he wandered far into the executive mansion before he was subdued.

Rep. Jason Chaffetz (R-Utah) pointedly told Pierson that the message should be “crystal clear -- if you dash at the White House we are going to take you down.” Intruders like Gonzalez, he said, could be armed with an explosive device or some other undetected weapon that could cause serious damage.

But Pierson said lethal force can only be employed if an individual poses an imminent threat to himself or herself or others. Based on reports, she said, agents appeared to use proper restraint.

Lawmakers remained angry throughout the exchange with Pierson, with several insisting that her demeanor and responses failed to project sufficient outrage over the incident.

“I believe that you have done a disservice to the president of the United States,” Rep. Steven Horsford (D-Nev.) told her at one point.

At the White House, spokesman Josh Earnest told reporters that Pierson had not offered her resignation to the president in light of the incident.