Secretary of State Hillary Rodham Clinton said Thursday that U.S. talks with the Afghan Taliban were “not a pleasant business, but a necessary one,” and said that the direct contacts had been made possible by President Obama’s aggressive military strategy against the insurgents.

“Only now are we beginning to see the kind of outreach that evidences a willingness to discuss the future,” Clinton told a Senate hearing. She described the discussions as “very preliminary.”

U.S. officials held three meetings this spring with Mohammed Tayeb al-Agha, an aide to Taliban leader Mohammad Omar but are unsure how the dialogue will proceed. They were reassured following the last contact when the Taliban, as agreed between the two sides, posted a coded acknowledgment of the discussion on its Web site, but there has not been another meeting, officials said.

Afghan President Hamid Karzai has publicly acknowledged the talks, although his government has not participated in them, according to U.S. officials, who spoke on the condition of anonymity because they were not authorized to discuss the initiative.

The administration has said repeatedly that any negotiations leading to a political settlement must be “Afghan-led.” But the Taliban has said it wants to speak directly with the United States, officials said. Its demands include establishment of an independent political office outside Afghanistan, most likely in Qatar, from where it can manage its side of any talks.

For now, the administration has sidestepped the issue by not sending its top diplomat on Afghanistan issues, Marc Grossman, to the table. Meetings with Agha in Qatar and Germany were attended by Frank Ruggiero, Grossman’s deputy, and Jeff W. Hayes, a Defense Intelligence Agency official who handles Afghanistan and Pakistan issues on the National Security Council staff, officials said.

Higher U.S. representation is being withheld, the officials said, until there is further progress and the Afghan government is brought into the talks.

Karzai has come at the issue from a different angle, forming a peace commission that includes leaders from various political blocs and civil society representatives, as well as former Taliban officials living openly in Kabul. He has successfully pushed for changes in a United Nations blacklist that will make it easier for the insurgent leadership to travel.

With administration urging, Afghanistan, Pakistan and the United States last month formed a “core group” to serve as a forum for the three to discuss negotiations with the Taliban.

Pakistan has pressed the United States to expand the talks to include the Haqqani network, an Afghan insurgent group based in the tribal regions along Pakistan’s western border that has ties to Pakistani intelligence. The administration believes the Taliban faction led by Omar, based in the southern Pakistani province of Baluchistan, is more amenable to negotiations and has ruled out talks with Haqqani representatives.

“The problem is that Americans believe that this [Haqqani] group can’t be separated from al-Qaeda and it will not shun violence. So they don’t think dialogue . . . could be of any advantage,” a Pakistani official said. Karzai, the official said, is amenable to talks with the network, “but the hurdle is from the American side.”

There is concern in Islamabad, the official said, “over being left out intentionally of U.S. talks with the Taliban,” which the Pakistani government learned about from news reports.

In testimony Thursday before the Senate Foreign Relations Committee, Clinton said that the ultimate success of negotiations would require participation from all countries in the region, including Pakistan, Russia, China, Iran and the Central Asian republics on Afghanistan’s northern border.

“We believe we’ve made progress with all of the neighbors,” she said, “including Iran.” Karzai and Pakistani President Asif Ali Zardari planned to travel to Tehran this week to attend an Iranian government conference on terrorism.

Special correspondent Shaiq Hussain in Islamabad, Pakistan, contributed to this report.