Gates, who said his visit is aimed at ensuring that Afghanistan's security situation improves, also met with Afghan military leaders during a tour of a military training center on the outskirts of Kabul.
Gates said that despite a rise in insurgent violence in Afghanistan during the spring, he remains convinced that U.S. and NATO forces are making steady progress against the Taliban.
Speaking at a Kabul press conference after talks with Karzai, Gates also corroborated reports that the U.S. military has been discovering Iranian-made weapons in western and southwestern Afghanistan.
When asked about alleged shipments of Iranian weapons destined for the Taliban, Karzai said he is uncertain about the source of such deliveries. But he said the governments in Kabul and Tehran have good relations and that trade between the two countries is good.
'Steep Obstacles'
Karzai said Iran has contributed millions of dollars to the Afghan economy through aid and trade.
That is the kind of help that Gates has been asking Afghanistan's neighbors to make. Speaking on June 3 at a security conference in Singapore, Gates called on Asian states to provide extra support for Afghanistan.
"I would urge others to step forward with assistance to Afghanistan in the areas of governance, reconstruction, and counternarcotics," Gates said. "It is clear that Afghanistan and its newly independent neighbors in central Asia face steep obstacles as they strive to make the transition into prosperous, secure, and fully sovereign nations."
Afghan Army Woes
Despite Gates' upbeat assessment about the fight against the Taliban in Afghanistan, he was told by the head of the Afghan National Army today that Kabul is not getting enough cooperation from neighboring Pakistan.
Afghan Army Chief of Staff General Bismullah Khan made the remarks to Gates as the two toured Camp Morehead, a military facility center on the outskirts of Kabul where the Afghan National Army's first battalion of commandos is being trained.
Officials in Afghanistan displayed what they said were Iranian-made land mines during Gates' visit (RFE/RL)