"We believe the commitment needs to continue and perhaps needs to be reinforced," Cheney said on a visit to Afghanistan's capital.
Standing beside Afghan President Hamid Karzai at a news conference, the vice president also said neighboring Pakistan has an obligation to battle insurgent activity along the border between the two countries.
He said the Pakistani government, like Karzai's, is a target for al Qaeda and other extremists. "They have as big a stake as anyone else," he said.
Cheney's remarks came after he met with Karzai at the Afghan leader's palace to discuss ways the country's fragile government can counter rising threats from al Qaeda and Taliban militants.
"During the last six years, the people of Afghanistan have made a bold, confident journey, throwing off the burden of tyranny and winning your freedom," he said with a nod to Karzai. "The process has been difficult, but the courage of the nation has been unwavering."
He said there has been remarkable progress in improving security forces and rebuilding in the country even as it struggles in a continuing war with insurgents.
Karzai also hailed progress, saying the Afghan army was getting stronger "day by day," but adding that international support will be needed for years to come.
As for his own political future, Karzai declined to say whether he will seek another term as president in elections scheduled next year. He said he wants to leave a legacy of strong political leaders in Afghanistan's future and that perhaps he could best achieve that by not running for re-election.
Cheney flew to the Afghan capital from Oman and took a helicopter straight to the presidential palace, where he greeted Karzai with a hearty handshake. The two strolled down a red carpet together, reviewing troops before heading inside the palace for their talks.
Reporters were not allowed to disclose Cheney's visit until he had arrived safely. It is Cheney's fourth vice presidential trip to Afghanistan. Cheney, who is on a 10-day foreign trip, visited Iraq earlier this week.
More than 8,000 people died in fighting in Afghanistan last year, making it the most violent year since 2001, when the U.S. invaded Afghanistan to oust the hard-line Taliban regime after the Sept. 11 attacks in the United States. Al Qaeda leader Osama bin Laden is believed to be hiding in rugged, mountainous areas along the Afghanistan-Pakistan border.
Cheney spokeswoman Lea Ann McBride said U.S. President George W. Bush asked Cheney to meet with Karzai in advance of a NATO summit next month in Romania.
Problems in Afghanistan will be a key topic at the NATO summit. NATO has about 43,000 troops in Afghanistan, but commanders have asked for more in areas of southern Afghanistan where the insurgency is the most active.
Troops from Canada, Britain, the Netherlands and the United States have done the majority of the fighting against Taliban militants. Forces from France, Spain, Germany and Italy are stationed in more peaceful parts of the country.
Canada, which has 2,500 troops in Kandahar province, recently threatened to end its combat role unless other NATO countries provide an additional 1,000 troops to help the anti-Taliban effort there. Canadian Defense Minister Peter MacKay said he expected a pledge for troops before or during the April 2-4 NATO summit.
The U.S. contributes one-third of the NATO force, and also has about 12,000 other U.S. troops operating independently from NATO. The Pentagon says that by late summer, there will be about 32,000 U.S. troops in Afghanistan - up from about 28,000 now.
An official who briefed reporters during the trip from Oman to Afghanistan said Cheney wanted to compare notes with Karzai to make the NATO summit a success.