Iraq’s ambassador to the United States warned that a Sunni militant group advancing on Baghdad would commit “ethnic cleansing” if President Obama doesn’t quickly intervene to stop them.

“Wherever they have the possibility, they will cleanse minorities, ethnic cleansing,” Ambassador Lukman Faily told The Guardian on Tuesday evening. 

{mosads}“Look at Mosul. They went into prisons, they executed the Shiite prisoners. They went into Mosul and they executed the Sunni imams who were reluctant about handing over their mosques to them.,” he added. “So what does that tell you? It tells you that they cannot coexist with others.”

Fighters representing the Islamic State in Iraq and Syria (ISIS) have captured key cities, including Mosul, and are nearing the capital city of Baghdad., threatening the Shiite-majority government of Prime Minister Nouri al-Maliki.

Observers have warned that the fighting could spark a sectarian civil war, with violence reported between Shiites and Sunnis in Baghdad. In the city of Baquba, just 44 miles away, 44 prisoners were reportedly executed in an attack. 

Faily has been lobbying members of Congress for the U.S. to intervene and launch air strikes in Iraq to target the militants.

President Obama is meeting with congressional leaders on Wednesday to discuss the deteriorating situation in Iraq, but the White House says no decision has been made on whether to launch strikes.

The Iraqi envoy stopped short of criticizing the administration but expressed concern that the U.S. must act quickly.

“That’s exactly our discussion with them,” Faily said. “We’re trying to highlight the urgency and the immediate threat to the integrity of the state, and they are coming up and saying, ‘Okay, what is the day-after scenario? Give us some visions as to the day-after scenario.”

Faily said he was hearing “positive signs” from the administration. He warned, however, that the longer Obama takes to make a decision, the harder it will be to root out the ISIS.

He said he strongly appreciated the work done by the Obama and Bush administrations, but said Iraq is frustrated by the U.S. hesitation. 

“As an Iraqi, and as the situation on the ground [changes], we’re seeing displacement, atrocities are taking place, [ISIS] capabilities are being enhanced, we’re handing over morale boosts to them, yes, it is frustrating,” he said.

“Yet at the same time, we have chosen the U.S. as our strategic partner, and we expect our partner to understand our sense of urgency and to work with us,” Faily added.