Speaking at a news conference with U.S. Defense Secretary Robert Gates, Karzai repeated his claim that Afghan security forces would take the lead in securing the nation within five years. But Gates suggested the U.S. can't wait that long.
"I would hope that we not only could meet the timelines that President Karzai has laid out, but that as more Afghans are trained we will be able to beat those timelines," Gates said.
Karzai's comments come a week after President Obama's announcement that while the U.S. was sending 30,000 more troops, they will start coming home in 18 months.
But many Afghans say they think that timetable is too short, and fear that - once again - they might be abandoned to civil war, reports CBS News correspondent Terry McCarthy from Afghanistan.
"It is very short-term and it will be better to renew and to prolong this one," Kabul aid worker Dil Agha told McCarthy.
The top U.S. military commander in Afghanistan, Gen. Stanley McChrystal, has set the goal of building the Afghan security force to 400,000 by 2013 - up from roughly 94,000 Afghan police officers and 97,000 soldiers.
When asked whether he would be able to sustain a larger Afghan force, Karzai said financial backing from the international community would be needed for years.
"For a number of years, maybe for another 15 to 20 years, Afghanistan will not be able to sustain a force of that nature and capability with its own resources," Karzai said.
Gates, the first member of Obama's Cabinet to visit Afghanistan since the president's announcement, said he and Karzai discussed how to recruit more Afghan soldiers and police to battle militants. "There is a realism on our part that it will be some time" before the Afghan security forces can stand on their own, he said.
Gates has sought to assure Afghans that the U.S. won't abandon them, but at the same time impose a sense of urgency.
"On a gradual, conditions-based premise, we will be reducing our forces after July of 2011," Gates said.
He added the U.S. expects the drawdown to be "a several-year process."
"Whether it's three years or two years or four years remains to be seen," he said. "But as President Obama has made clear, this is not an open-ended commitment on the part of the United States."
Gates also addressed a fear among the Afghan people that more troops in their country will result in more violence and civilian casualties.
"Our top priority remains the safety of civilians," he said.
Just before the two leaders spoke, the Afghan government accused NATO forces of killing civilians during a pre-dawn strike Tuesday in eastern Afghanistan.
NATO said seven militants were killed, but no civilians were injured or killed. A spokesman for the Afghan Interior Ministry said some civilians died in the attack aimed at a Taliban operative in Laghman province. Provincial police chief Gen. Abdul Karim Omeryar said 12 Afghans died, including one woman.
During the press conference, Karzai reaffirmed his commitment to fight corruption. The president, who won re-election to a second term in a ballot marred by fraud, is under intense international pressure to nominate a slate of reformists, and it will be the first test of his willingness to meet his pledge to reform the government.
"We will try our best as Afghans to present a Cabinet to the Afghan people that can also be appreciated and supported by the international community," Karzai said.
Karzai said he was ready to send parliament 40 percent of his Cabinet nominees now, but that he would meet lawmakers' demand to send a full, not partial, list to the assembly. He said he would send the full list to the parliament next Tuesday or Wednesday or earlier. He said ministers with proven track records of service would remain in the Cabinet, although he did not say if they would stay in their same posts.
Karzai has repeatedly argued that while there is corruption in the Afghan government, there is also corruption within international contracting processes.
Gates said the U.S. and other international partners bore some responsibility because the billions of dollars the international community has been spending in Afghanistan has enabled a climate of corruption.
"I think President Karzai has taken responsibility for dealing with the problem in so far as the Afghans are concerned," Gates said. "We have to do what we can do to help make it more difficult for people to misbehave."