ISIS Still on the Attack, Despite Internal Strife and Heavy Losses

The Islamic State is facing growing dissension among its rank-and-file fighters and struggling to govern towns and villages it has seized, but the militant Sunni group is still managing to launch attacks and expand its ideological reach outside of Iraq and Syria, senior American officials said.

In the seven months since allied warplanes in the American-led air campaign began bombing select Islamic State targets, the Sunni militancy, while marginally weaker, is holding its own, senior defense and intelligence officials said.

Pentagon officials expressed only cautious optimism on Thursday after the Islamic State lost much of the central Iraqi city of Tikrit following more than a week of fierce fighting, warning that it would be as difficult for Iraqi forces to hold the city as it was to liberate it. And even as the militants had a last stand in Tikrit, Islamic State fighters were mounting one of the fiercest assaults in months in the city of Ramadi, west of Baghdad.