Panetta, speaking to reporters traveling with him to Kyrgyzstan, stressed the killings of 16 Afghans Sunday allegedly by a U.S. soldier, or the earlier inadvertent Koran burnings on a U.S. base were tragic.
However, he said, they should not detract from the mission of defeating al-Qaida and preventing Afghanistan from ever again becoming a safe haven, the Defense Department said on its Web site.
"The level of violence [in Afghanistan] ... is at its lowest point in five years," he said. "It's down 24 percent this year alone."
The secretary said Afghan army and police forces now lead security efforts for half of their nation's people, and the transition from NATO to Afghan security responsibility is well into its second stage, scheduled to be completed by 2014 end. The 23,000 U.S. troops remaining from the 2010 surge are set to leave Afghanistan by September.
Panetta said fewer than 70,000 U.S troops would remain by October and their drawdown is set to conclude before 2015.
"I think it's very important for policy makers to keep [their] eye on the target," Panetta said. "The test has to be whether or not Afghanistan is working with us to maintain the strategy.
"We need to ensure that what happened over these last few weeks does not happen again ... These are serious matters," he added. "We're on the right path now ... I do not believe there is any reason at this point to make any [strategic] changes."