WASHINGTON — Secretary of State Rice praised President Karzai of Afghanistan as a strong leader yesterday, following an assassination attempt that highlighted the threats to the American-backed government more than six years after the fall of the Taliban.

“What it underscores for me is that Afghanistan has … determined enemies who will do anything to disrupt the democratic progress that the Afghan people have made,” Ms. Rice said following a meeting with the newly named U.N. envoy to Afghanistan.

“President Karzai is a strong leader and he has responded, I think, in a strong fashion to this,” Ms. Rice said. “They will certainly find the perpetrators and they will bring them to justice.”

The attack Sunday during an outdoor ceremony in Kabul killed three people, wounded eight, and sent Mr. Karzai and foreign ambassadors scurrying for cover. The Taliban claimed responsibility but said additional attackers were involved.

“Thankfully, President Karzai was not harmed,” the White House press secretary, Dana Perino, said yesterday.

“The terrorist threat is real, it is deadly, and defeating this enemy has to be a top priority of the United States, of the Afghan government, of the Iraqi government and the NATO alliance,” Ms. Perino said.

The strike launched so close to Mr. Karzai was a serious security lapse at a time when the Afghan police and army are expanding and the government is demanding greater control of security, still provided in much of the country by America and NATO-led forces.

A spokesman for the defense ministry, General Mohammad Zahir Azimi, said authorities were investigating who could have helped the assailants.