The U.S. Secret Service chief faced withering criticism Tuesday from lawmakers outraged over security breaches at the White House, as she pledged to revamp the agency to prevent an embarrassing repeat.

The grilling before a House panel came after a man carrying a knife scaled the White House fence on September 19 and made it deep into the presidential mansion -- the latest in a string of scandals involving the Secret Service.

An intruder armed with a knife who jumped a fence and sprinted across the White House lawn, got much further into the presidential mansion than previously thought, a report said Monday.

The Washington Post said the man rushed in through the front door of the White House and ran into the ceremonial East Room, one floor below the private residence of President Barack Obama and his family.

A White House official on Sunday played down a report that it took the Secret Service days to realize a man shot at the presidential residence in 2011, while President Barack Obama's daughter was at home.

The Washington Post report came amid new scrutiny on the agency tasked with protecting the president, after a series of recent security lapses, including one earlier this month that saw an intruder armed with a knife jump over a security fence and burst into the White House.

National Security Adviser Susan Rice reaffirmed U.S. commitment to supporting Syria's moderate opposition at a meeting in Washington with a delegation from the Syrian National Coalition, the White House said Saturday.

The Friday meeting came as the United States and coalition partners broaden air strikes against the Islamic State group in Syria, with a defense official telling Agence France-Presse that "near continuous" combat sorties were being conducted there, as in Iraq.

American leadership is as strong as ever despite a slew of challenges, from the fight to eradicate Islamic State militants to a deadly Ebola epidemic and efforts to tackle climate change, President Barack Obama said Saturday in his weekly address.

Obama, the reluctant warrior who took office nearly six years ago promising to end costly wars, instead now finds himself launching a new conflict -- against the Islamic State jihadists -- that the White House freely admits will stretch past his departure from office in January 2017.

The White House on Friday praised allies Britain, Denmark and Belgium for joining the military coalition battling the Islamic State (IS) group in Iraq.

"We certainly welcome the recent vote that occurred in the British parliament," White House spokesman Josh Earnest said.

A homeless U.S. army veteran who jumped a fence and ran into the White House with a knife had more than 800 rounds of ammunition in his car, a court heard Monday.

Omar Gonzalez, 42, appeared in U.S. District Court as Barack Obama's spokesman said the president is "obviously concerned" by Friday's stunning security breach.

A man with a knife who scaled the White House fence and burst through the mansion's front doors is due in federal court Monday, after the incident sparked a wide-ranging security review.

Omar Gonzalez, 42, is facing charges of unlawfully entering a restricted building or grounds while carrying a deadly or dangerous weapon. He faces up to 10 years in prison.

The U.S. Secret Service said Saturday it has launched a comprehensive review of White House security procedures after an intruder scaled a fence, sprinted across the lawn and entered the presidential residence.

The White House -- the president's workplace and home -- is generally regarded as one of the most secure and protected places on the planet.

A man triggered an evacuation at the White House late Friday after he scaled a fence and made it into the building before being captured.

U.S. President Barack Obama and his family were not at the White House at the time, though officials and journalists were rushed out of the building during the disturbance that began on the North Lawn around 7:20 pm (2320 GMT) Friday, the Secret Service said.