Obama sends letter to Congress , stressing dam 's strategic importance . ISIS wants to keep Mosul Dam working , CNN analyst says . Comment: Forces have retaken one side of the dam . CNN 's Barbara Starr , Ali Younes , Mohammed Tawfeeq , Alexander Felton , Mariano Castillo and Fredricka Whitfield contributed to this report . Smoke rises from the horizon , and buildings are ablaze in the battle to retake it .
Obama sends letter to Congress , stressing dam 's strategic importance . ISIS wants to keep Mosul Dam working , CNN analyst says . Comment: Forces have retaken one side of the dam . Smoke rises from the horizon , and buildings are ablaze in the battle to retake it .