The top US and NATO commander in Afghanistan said Monday it will be years before coalition forces can make a complete handoff to Afghan security forces, despite the arrival of thousands of new troops beginning this month and signs of diplomatic progress. Army Gen. David McKiernan told newspaper executives gathered at The Associated Press annual meeting that militant havens across the border in Pakistan remain a challenge. And while he said that the Afghan army is now leading 60 percent of missions in Afghanistan, Afghan police lag in their ability to provide security. Many of the 21,000 new troops arriving this month will be directed to the nation's southern region and will be trained to work as mentors to Afghan troops in addition to working in counterinsurgency operations. "What we want to do is make a significant impact on the foundation of security ... and continue to move toward developing sufficient Afghan capacity and specifically, their army, their police, so at some point we can get to a tipping point where they lead the security in this country," he said.