President Barack Obama had watched with alarm for most of the summer as an al-Qaida-linked insurgency seized more and more territory in northern Iraq. But it wasn't until Thursday, when Obama learned that genocide could be imminent, that the president decided the U.S. military had to act.
Reports streamed into the Situation Room that morning from U.S. diplomats and intelligence officials: Stories of mass executions, women being enslaved as child brides, members of a small religious group trapped on a mountain and potentially dying of thirst.
Then the president, for the first time, was given an assessment that thrust the crisis into a new category.
As one top official put it: ''I had not heard the word `genocide' used in the Situation Room before.''
By the time 90-minute meeting ended, it was clear Obama planned to order humanitarian aid to be airdropped to the Yazidis, a religious minority being targeted by the Islamic State militant group. But advisers were unsure whether Obama would go one step further: airstrikes in Iraq, just three years after the U.S. pulled out from a war that Obama never liked.
As the fast-growing Sunni rebellion overran major Iraqi cities in early June, Obama began weighing his options. A U.S. aircraft carrier was ordered into the Persian Gulf, and Obama began dispatching hundreds of special forces to advise Iraqis and protect U.S. personnel.
On one point, Obama was firm: No ground troops would be returning to Iraq. Yet the prospect of targeted airstrikes hung in the air. Obama was reluctant to take that step, but it could prove critical to preventing a security collapse in Iraq.
In July, some lawmakers were demanding immediate drone strikes, while others were urging the opposite. A top senator threatened to block sales of arms to Iraq, and House of Representatives lawmakers easily passed a resolution to bar Obama from sending forces into Iraq long-term without their approval.
Pentagon leaders were reviewing what U.S. assistance might help Iraq's beleaguered military, while diplomats pressed Iraqi leaders for a political transition that would bring disenfranchised Sunnis and Kurds into the government.
Wednesday was a tipping point. Obama was in three days of meetings with nearly 50 African heads of state who had come to Washington at his invitation. But roughly 6,000 miles (9,655 kilometers) away, the Yazidis were in trouble, having fled to the mountains to escape the extremists.
Senior administration officials met throughout