The Haditha Dam is 175 miles from Baghdad, 220 miles from Erbil and 270 miles from Mount Sinjar.

“I think the strikes the United States took are very much in line with what President Obama said were the guiding principles of military action in Iraq,” Defense Secretary Chuck Hagel said Sunday at a news conference with the Georgian defense minister in Tbilisi. “If that dam would fall into ISIL’s hands,” he said, using another acronym for ISIS, “or if that dam would be destroyed, the damage that would cause would be very significant, and it would put a significant, additional and big risk into the mix in Iraq.”

A break of the Haditha Dam, military officials said, could flood Baghdad’s airport and threaten Americans in Iraq. That rationale is similar to the one used when American warplanes bombed ISIS militants who controlled the Mosul Dam. But such a definition gives the White House wide latitude to support Iraqi forces in a sustained military offensive against the group across the country.

The battles over the two dams are part of a war for water that ISIS has waged since it swept into Iraq, bent on carving out a caliphate in territory spanning Iraq and Syria. The dams, which control the Tigris and Euphrates Rivers, have become a valued asset for both sides.

The towns struck by the United States over the weekend, in Anbar Province, were captured by ISIS extremists in late June, shortly after they stormed the northern city of Mosul. The territory the militants held — which included the towns of Qaim, Rawa, Ana and Barwana — gave ISIS a supply route to Syria along a strategic highway, and put its fighters within reach of the Haditha Dam.