U.S. Defense Secretary Leon Panetta is in Afghanistan to check on the progress of U.S.-led counterinsurgency efforts, which he says reached a “turning point” this year after a decade of fighting the Taliban.

Panetta arrived in Kabul on Tuesday for meetings with U.S. military commanders and Afghan officials. On the flight to the Afghan capital, he told reporters the Afghan military and police are better prepared to take responsibility for securing the country as U.S.-led NATO troops gradually withdraw.

U.S. President Barack Obama issued an order earlier this year for the withdrawal of 10,000 American troops by the end of 2011 and the pullout of another 23,000 by next October. NATO plans to continue transferring security control of Afghan provinces to Afghan forces during that period.

But the transition process has been complicated by worsening U.S. relations with Pakistan, whose long border with Afghanistan is a haven for Taliban and al-Qaida militants who attack NATO and Afghan troops.

In his remarks to the media, Panetta said the United States “cannot win the war in Afghanistan without being able to win in our relationship with Pakistan as well.” He said the top U.S. commander in Afghanistan, General John Allen, has reached out to Pakistani commanders to try to rebuild cross-border security cooperation.

Pakistan barred NATO from using Pakistani border crossings to send supplies to landlocked Afghanistan last month in retaliation for a NATO air strike that killed 24 Pakistani soldiers along the frontier. NATO says its aircraft were trying to attack militants and denies Pakistani accusations that it deliberately targeted the Pakistani troops.

Pakistan has taken other punitive measures in response to the November 26 incident, including ordering the U.S. military to vacate a Pakistani air base that serviced U.S. drones involved in attacks on militants in the border region.