The departure of American troops from Iraq will likely increase instability and worsen tensions among militant groups, the top U.S. general in Iraq predicts. As the U.S. troops pull out in the coming weeks, Gen. Lloyd J. Austin III said he expects the Sunni extremist group al-Qaida in Iraq to expand, while Shiite militias based mostly in southern Iraq seek to increase their capabilities, The Washington Post reported. \"Al-Qaida will continue to do what it\'s done in the past, and we expect that it will increase in its capability,\" Austin said. Speaking to journalists at a briefing at the U.S. Embassy in Baghdad Monday, Austin said: \"There\'s likely to be setbacks, some tough times in the days ahead. As we leave, we can expect to see some turbulence in security initially.\" But, he said, \"I\'m hopeful that the right things will continue to happen.\" The Post noted Iraqi security forces lack the ability to wage an effective defense against external threats at a time when tensions are mounting in neighboring Syria and between Iran and the West. Austin said it\'s likely the Iraqi government would consider allowing some U.S. trainers to return to the country after the withdrawal to help strengthen the Iraq army\'s defensive abilities. But no negotiations are expected until after the withdrawal is complete. Under a 2008 U.S.-Iraq security agreement, all American troops must leave Iraq by the end of December.