In an interview with ABC News, Karzai was asked how he felt when he heard US President Barack Obama criticise his government last month for being corrupt and vow there would no longer be a "blank cheque" for US assistance.
"We really never had a blank cheque," Karzai said. "But we're grateful even for the little money that's come to Afghanistan, even for the little help that's come to Afghanistan."
"We have no right over the American people to pay for us or to help us. This is our country. We must protect it ourselves and provide for it ourselves," Karzai said.
"So help from America is welcome. And even a penny is worth billions for us. In terms of gratitude, we are grateful for the help that we have received."
In a speech last month announcing that he would send 30,000 more US troops to Afghanistan, Obama put pressure on Karzai to root out corruption in his administration.
Since the United States led an invasion of Afghanistan in 2001 to topple the Taliban movement after the September 11 attacks, Washington has spent about $171.4 billion to keep the Taliban at bay. About 900 US soldiers have died fighting the Taliban and al Qaeda in Afghanistan.
In his troop increase announcement last month, Obama vowed to begin bringing US soldiers home in 18 months and start handing off responsibilities to Afghan forces.
Karzai, who had initially urged patience if his government could not meet a 2011 deadline for assuming responsibility for security, said in the interview he thought the deadline would help push Afghans to be ready.
"In a sense ... that exit date is good for us," he said.
"It pushes us to harder work, to strengthen our forces, to train our forces, to be realistic about life in Afghanistan and to think many times over of how better we can use our own resources and live with our own means and protect our own country."
Karzai said he knew "America will not be completely out in another 18 months or 15 months."
"We know the US and our other allies will be with us for many more years to come," he said. "But even then, Afghanistan needs to be a self-sustaining country in all aspects of the needs of ... this country."
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