NATO is still about 450 short of its target for a training force to assist the Afghan security forces, and while that gap apparently was not filled during Friday's session, Clinton said she was not discouraged.
"We have a relatively small gap that we're still working to fill. I'm very convinced we'll get that filled," she said, adding: "For me, the glass is way more than half full."
Mark Sedwill, the senior NATO civilian representative in Afghanistan, told reporters later that the Tallinn meeting's agreement on starting a transition to Afghan control this year will require endorsement by the Afghan government. That is supposed to happen at a July conference in Kabul.
The next step would be an announcement at a NATO summit meeting in November of the first provinces targeted for transition to Afghan control, Sedwill said.
NATO Secretary General Anders Fogh Rasmussen said the 28-nation alliance is on track with its new strategy for winding down the war in Afghanistan, despite security setbacks and a continuing shortage of foreign trainers for the fledgling Afghan police and army.
"Our aims in 2010 are clear: to take the initiative against the insurgents, to help the Afghan government exercise its sovereignty, and to start handing over responsibility for Afghanistan to the Afghans this year," he said.
He said a meeting of NATO foreign ministers, including Clinton, agreed on what it will take to create conditions enabling Afghans to assume control of their own country. He was not specific about what those conditions will be, but said progress in that direction is important in order to avoid further erosion of public support for the war effort.
"Where it occurs, the transition must be not just sustainable but irreversible," Fogh Rasmussen told a news conference at the conclusion of the two-day meeting.
"Citizens in Afghanistan and in all troop contributing countries are demanding visible progress, and they are right to insist on that," he added. "We should have no illusions. Making progress will not be easy and will not be quick. But based on what we see on the ground now, it is happening."
He added that looking ahead to a winding down of the war does not mean the allies will leave before the mission is accomplished.
"It will not be a run for the exits," he said.
In earlier remarks, Fogh Rasmussen offered a mostly upbeat assessment to the gathering.
"Increasingly this year the momentum will be ours," he said.
Fogh Rasmussen asserted that the Afghan government, which has been hampered by a Taliban insurgency, political corruption, a dysfunctional economy and a dependence on foreign assistance, is starting to take more responsibility for running the country's affairs.
"We are preparing to begin the process of handing over leadership, where conditions allow, back to the Afghan people," he said. "The future of this mission is clear and visible: more Afghan capability and more Afghan leadership."
During Friday's meeting, which was closed to the press after Fogh Rasmussen made brief introductory remarks, Clinton was expected to press other NATO nations to provide more trainers for Afghanistan's police and military forces as part of preparations to withdraw Western troops from there by summer 2011.
Fogh Rasmussen said Thursday that an additional 450 trainers are needed for Afghanistan's security forces. Insufficient numbers of foreign trainers has plagued the U.S.-led war effort for years, although the shortfall has narrowed in recent months.
Friday's session also was focusing on a NATO initiative aimed at stimulating the Afghan economy by making it a priority for all foreign contingents operating in Afghanistan to hire Afghan contractors and purchase Afghan goods and services whenever possible.