Far fewer refugees remain on Iraq's Sinjar Mountain and a US-led rescue mission is unlikely, US officials say.
A team of US military personnel assessed the situation and reported that several thousand refuges were on the mountain but appeared to be in good condition, the Pentagon said in a statement.
Tens of thousands had been reported on the mountain last week.
Defence Secretary Chuck Hagel credited airdrops of food and water for sustaining those on the mountain and airstrikes for pushing back Islamic militants and allowing refugees to leave.
''As a result of that assessment, I think it's most likely far less likely now that we would undertake any kind of specific humanitarian rescue mission that we have been planning,'' Hagel told reporters as he returned to Washington from a world tour.
''That doesn't mean that we won't,'' he said.
Iraq remained a troubled country, Hagel said, but he called the assessment of Sinjar Mountain a good news. The US efoort in Iraq was "not complete.''
Attacks across Iraq's north and west by the Islamic State group and its Sunni militant allies this summer have displaced members of the minority Christian and Yazidi religious communities and threatened neighbouring Iraqi Kurds in the autonomous region.
Thousands of Yazidis on the mountain were able to leave each night over the last several days.