Obama: U.S. tried to rescue Kayla Mueller from ISIS last summer

President Obama said that Kayla Jean Mueller, the 26-year-old American woman held by Islamic State of Iraq and Syria (ISIS) militants who was confirmed dead Tuesday, was among the hostages the U.S. sought to rescue in a secret mission that failed in the summer of 2014.

"I deployed an entire operation -- at significant risk -- to rescue not only her but the other individuals who had been held, and probably missed them by a day or two," the president said in an interview with Buzzfeed News Tuesday.

After the first American hostage, journalist James Foley, was beheaded by ISIS in August 2014, the administration confirmed it had launched a secret mission to Syria to rescue American hostages. Intelligence agencies believed the hostages were being held at an oil refinery, but the several dozen special operations forces who flew into Syria did not find them.

• American ISIS hostage is dead, family confirms
• U.S. tried to rescue hostages in Syria, but couldn't find them

The administration only went public with the operation because some media outlets were preparing to report on the mission, an administration spokeswoman said at the time. Mr. Obama's remarks Tuesday were the first confirmation that Mueller - whose identity was kept a secret after her capture in August 2013 - was among the hostages the U.S. hoped to rescue.

Her identity was revealed last week after ISIS claimed that she was killed by a Jordanian airstrike, a claim that nation has refuted. The exact cause and date of Mueller's death is still inconclusive, according to her family.

As ISIS executed three other Americans - Foley, along with journalist Steven Sotloff and aid worker Peter Kassig - the official U.S. policy of not paying ransoms for hostages has come under fire.

But in the interview, Mr. Obama objected to suggestions that the U.S. could have done more.

"I don't think it's accurate ... to say that the United States government hasn't done everything we could," Obama said. "We devoted enormous resources and always devote enormous resources to freeing captives or hostages anywhere in the world."

He also said telling the families of the hostages that the U.S. will not pay ransoms is "as tough as anything I do."