WASHINGTON — Airstrikes on towns in northern Iraq seized by Islamist militants began late Thursday in what Kurdish and Iraqi officials called the first stage of an American-led intervention to blunt the militants’ advance and provide emergency aid to tens of thousands of refugees.
The Pentagon firmly denied that American forces had begun a bombing campaign. But Pentagon officials said it was possible that allies of the United States, either the Iraqi or Turkish militaries, had conducted the bombing.
Kurdish and Iraqi officials attributed the bombing campaign to American forces. An announcement on Kurdish television of what was described as an American intervention prompted street celebrations and horn-honking by residents of towns under seige by the Islamic State in Iraq and Syria.
Anwar Haji Osman, deputy minister of the Peshmerga, the Kurdish military force, said in the televised statement that his forces had contact with the Americans and that the bombings had been carried out by fighter jets.
Kurdish officials said the bombings had initially targeted ISIS fighters who had seized two towns, Gwer and Mahmour, near the main Kurdish city of Erbil. A top Iraqi official in Baghdad close to Prime Minister Nuri Kamal al-Maliki of Iraq said that the Americans had consulted with the Iraqi government Thursday night about starting the campaign, the government had agreed and the bombing had begun.
Earlier in the day, administration aides had said Mr. Obama was considering airstrikes or airdrops of food and medicine to address a humanitarian crisis among as many as 40,000 members of religious minorities in Iraq, who have been dying of heat and thirst on a mountaintop where they took shelter after death threats from ISIS fighters.
In meetings with his national security team at the White House on Thursday morning, Mr. Obama weighed a series of options, ranging from dropping humanitarian supplies on Mount Sinjar to mounting military strikes on the fighters from ISIS who are now at the base of the mountain, a senior administration official said.
“There could be a humanitarian catastrophe there,” a second administration official said, adding that a decision from Mr. Obama was expected “imminently — this could be a fast-moving train.”
The administration official said that “the president is weighing both passive and active options,” defining passive action as dropping humanitarian supplies. “More active, we could target the ISIL elements that are besieging the base of the mountain,” he added, using an alternative name for ISIS, the Sunni extremist group that has taken control of much of northern Iraq.
The White House declined to say whether Mr. Obama was weighing airstrikes or airdrops in Iraq, but the press secretary, Josh Earnest, said the United States was disturbed by what he described as “cold and calculated” attacks by ISIS on religious minorities in Iraq.
“These actions have exacerbated an already dire crisis, and the situation is nearing a humanitarian catastrophe,” Mr. Earnest told reporters. The campaign of attacks by ISIS, he said, “demonstrates a callous disregard for human rights and is deeply disturbing.”
Asked specifically about military options, Mr. Earnest said, “I’m not in a position to rule things on the table or off the table.” But he reiterated that there would be no American combat troops in Iraq and that any military action would be extremely limited.
“There are many problems in Iraq,” he said. “This one is a particularly acute one, because we’re seeing people persecuted because of their ethnic or religious identities.”
Mr. Earnest added: “There are no American military solutions to the problems in Iraq. These problems can only be solved with Iraqi political solutions.”
Mr. Obama made no mention of imminent military action as he traveled to Fort Belvoir in the Virginia suburbs on Thursday to sign legislation to overhaul the troubled Department of Veterans Affairs. Top officials were in the meantime gathering at the White House to discuss the possible Iraq action.
The administration had been delaying taking any military action against ISIS until there is a new Iraqi government. Both White House and Pentagon officials have said privately that the United States would not intervene militarily until Mr. Maliki stepped down.
But administration officials said on Thursday that the crisis on Mount Sinjar may be forcing their hand. About 40 children have already died from the heat and dehydration, according to Unicef, while as many as 40,000 people have been sheltering in the bare mountains without food, water or access to supplies.
The administration officials spoke on the condition of anonymity because they were not authorized to speak publicly. One official said that any military action would be “limited, specific and achievable,” noting that Mr. Maliki’s political party was supposed to announce a new candidate for prime minister on Thursday, but had not yet.