KABUL/SINGAPORE (Reuters) - Defense Secretary Robert Gates said on Saturday there could be political talks with the Afghan Taliban by the end of this year if NATO made more military advances and put pressure on the insurgents.
In the clearest signal yet of efforts to seek reconciliation with the Taliban, Gates told a security conference in Singapore that the gains on the Afghan battlefield were laying the ground for talks with the insurgents.
He later flew to Kabul for his final visit as Pentagon chief and told a joint news conference with President Hamid Karzai that it was imperative to achieve success.
"No doubt, there is weariness in both our countries over the duration and costs of this conflict," Gates said.
He said it was important to achieve the war aims laid down by President Barack Obama, despite the high cost, flagging support and tension between Washington and Karzai over issues such as civilian casualties caused by troops from the NATO-led International Security Assistance Force (ISAF).
Both Gates and Karzai said the Taliban would have to sever ties with al Qaeda, agree to abide by the Afghan constitution and lay down their arms if they wanted a political role.
In his earlier remarks to the Shangri-La Security Dialogue in Singapore, Gates said the generally accepted view was that the war in Afghanistan would ultimately have to end with a political settlement.
But that could not happen until the Taliban and other insurgents understood "they cannot win militarily," he added.
He said U.S., NATO and Afghan forces had made significant battlefield gains, particularly in the Taliban heartland in the south, over the past 18 months. If those gains could be sustained "perhaps this winter the possibility of some kind of political talks on reconciliation might be substantive enough to be able to offer some hope of progress."
Gates's comments follow reports that the U.S. has begun a secret engagement with the Taliban as it begins to withdraw troops from Afghanistan in July as part of a process to hand over all combat operations to Afghan security forces by 2014.
Officials in several countries have said there have been contacts but these do not yet constitute a peace process.
Gates, who steps down as defense secretary at the end of June, appeared, in comments on the way to Afghanistan, to leave open the possibility of a shift in the U.S. mission.
"I think that once you've committed, that success of the mission should override everything else because the most costly thing of all would be to fail," he said before landing in Kabul.
"Now that does not preclude adjustments in the mission or in the strategy, but ultimately the objective has to be success in the mission that has been set forth by the president."
His visit to Kabul came four days after withering criticism by Karzai over a spate of recent civilian casualties inflicted by ISAF troops, including the deaths of several children in a misguided air strike in southern Helmand last week.
Karzai warned ISAF troops not to become an "occupying force" and said such incidents would no longer be tolerated.
On Saturday, he raised the issue at the news conference, saying bluntly: "We cannot take this any more."
"I am keenly aware that some of these ISAF military operations have at times impacted the Afghan people in unwelcome ways ... losses we mourn and profoundly regret," Gates said.
Military leaders are finalizing recommendations to Obama about how to begin withdrawing U.S. forces from Afghanistan in July. Obama promised the drawdown when he deployed additional forces last year in a bid to stop a resurgent Taliban.
Gates, who said his 12th and final visit was mainly a chance to bid farewell to service members, declined to be drawn on the pace of troop withdrawals, saying he didn't want to "pre-empt the president's decision space."
ISAF trainers are working to prepare Afghan forces to take full responsibility for security by the end of 2014, a task hindered in the past by lack of equipment, and low retention and literacy rates.
"For this upcoming transition period to be successful, the Afghan government and security forces must be willing to step up and take more and more responsibility for governing and defending their own territory," Gates said.
Additional reporting by Paul Tait; editing by Tim Pearce