By Barbara Starr and Elise Labott
CNN has learned new details about what is contained in the U.S. intelligence assessment that alleges the Syrian regime was behind a deadly chemical weapons attack outside Damascus, Syria, last week.
According to senior U.S. officials, the assessment contains evidence showing senior regime officials making preparations for a massive chemical attack in the area where the incident occurred - the evidence is part of a "body of intelligence beforehand" that links the regime to the attack, as one of the officials described it.
It also includes evidence of senior regime officials discussing the attack afterward, acknowledging a realization the event was already getting massive attention and discussing that it would be wise to lay low for a while and refrain from launching such massive chemical attacks in the near future, the officials said.
In addition, the intelligence shows there was increased intensive shelling in the area after the attack, the officials said.