President Obama to Assad: 'The World Is Watching'

And, of course, the president also spoke out today about the lethal stockpile of chemical weapons in the hands of the brutal regime in syria. Chemicals so deadly one drop can kill within minutes and... See More

And, of course, the president also spoke out today about the lethal stockpile of chemical weapons in the hands of the brutal regime in syria. Chemicals so deadly one drop can kill within minutes and martha raddatz on these weapons and whether it means the u.S. May be forced to take action. 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. Sarin is an extremely toxic substance that can kill a person in a matter of minutes with only one drop. The victims suffocated from the paralyzing effects of the toxin. This new intelligence has the obama administration so concerned, harsh warnings came today from the president himself. I want to make it absolutel clear to assad and those under his command, the world is watching. The use of chemical weapons is and would be totally unacceptable. If you make the tragic mistake of using these weapons, there will be consequences and you will be held accountable. Reporter: A senior official tells abc news that there are contingency plans for military action if the weapons become a threat. The syrian regime said today it would not use chemical weapons under any circumstance, but president assad's father used them, diane, and assad himself has been massacring his citizens for nearly two straight years, as you know. Thank you, martha raddatz, reporting in on syria tonight. Now we turn to a health