The Obama administration is considering launching a humanitarian relief operation for Shiite Turkmen in northern Iraq who have been under siege for weeks by Islamic State militants, U.S. defense officials said Wednesday.

The mission, if it went forward, would be the second recent U.S. military humanitarian intervention in Iraq. U.S. cargo planes dropped tons of food and water to displaced Yazidis on Mount Sinjar in northern Iraq earlier this month, supported by U.S. airstrikes on nearby Islamic State fighting positions.

The administration is now focused on the imperiled town of Amirli, which is situated about 105 miles north of Baghdad and just a few miles from Kurdish territory. An estimated 12,000 to 15,000 people are estimated to have no access to food or water.

The head of the United Nation's assistance mission in Iraq, Nickolay Mladenov, earlier this week called for urgent action in Amirli and described the situation as desperate.

Three U.S. defense officials said a humanitarian mission is under consideration. They spoke on condition of anonymity because they could not discuss internal administration deliberations by name. The timetable for a decision on whether and how to go ahead with the mission was not immediately clear.

The siege of Amirli is part of the Islamic State's offensive, which seized large swaths of western and northern Iraq this summer and pushed further in neighboring Syria.

Residents have put up fierce resistance since the siege began, preventing the Sunni militants from successfully taking over the town. But the militants have, in turn, cut off the town, leaving thousands without access to food, water and medicine, despite recent airdrops by the Iraqi military.

Like other minorities in Iraq such as the Christians and the Yazidis, the Shiite Turkmen community has also been targeted by the Islamic State, which views them as apostates. Tens of thousands of Turkmens, Iraq's third-largest ethnic group, have been uprooted from their homes since the Islamic State took Mosul, the northern city of Tikrit and a spate of towns and villages in the area.

Dr. Ali al-Bayati, head of an Iraq-based humanitarian group called the Turkmen Saving Foundation, said Wednesday that at least 15,000 civilians, including many women and children, remain trapped in Amirli without access to food or water.

He said the streets are blocked by Islamic State fighters and the only way out is by air. The nearest Iraqi ground force is in the town of Toz Khormatu, which has seen intense clashes in recent weeks. Electricity and water are completely cut off in Amirli, according to al-Bayati.

Al-Bayati said airdrops from the Iraqi military have provided residents with desperately needed staples like rice, oil and cheese, as well as weapons to help them resist the Islamic State. However the residents often go 10 days without any airdrops successfully reaching them.

David Pollock, a former State Department official and now a fellow at the Washington Institute for Near East Policy, said Tuesday the U.S. military could assist in opening a land corridor into Kurdish territory for the besieged Turkmen.

"It's a very urgent situation," Pollock said.