he's marine corporal general joseph doneford and replaces general john al llen, nominatedo head forcesf his involvement in the sex scandal that brought down former cia director david petraeus. >>> in foreign news, new intelligence reports, indicate syria's government may be preparing to use chemical and biological weapons against the rebels. in response though, the u.s. and its allies are considering military options. here's abc's martha raddatz. >> reporter: the latest intelligence is alarming. officials telling abc news the u.s. is now seeing specific signs that the syrian regime may be preparing to use the chemical sarin against opposition forces. sarn is an extremely toxic substance that can kill a person in matter of minutes with only one drop. the victim suffocated from the paralyzing effects of the toxin. this new intelligence has the obama administration so concerned, harsh warnings came from the president himself. >> i want to make it absolutely clear to assad and those under his command the world is watching. the use of chemical weapons is and would be totally unacceptable. i