NEW : White House wo n't rule out more support for rebels , has n't verified latest claim on chem weapons . Chairman of the Joint Chiefs points to lack of intelligence as major factor in military involvement in Syria . Syrian opposition leaders do n't trust the Obama administration , experts on the region say . Distrust stems from the U.S. debate over chemical weapons , likely to continue after latest claims .
NEW : White House wo n't rule out more help for rebels , has n't verified latest claim on chem weapons . Chairman of the Joint Chiefs points to lack of trust as major issue in military involvement in Syria . Syrian opposition groups do n't trust the Obama administration , experts on the region say . Distrust stems from the U.S. debate over chemical weapons , likely to reignited after latest claims .