The White House said that it attempted to rescue U.S. hostages held by ISIS, including James Foley, who was beheaded in a video distributed by the terror group yesterday.

“Earlier this summer the president authorized an operation to attempt the rescue of American citizens who were kidnapped and held by ISIL against their will in Syria,” Assistant to the President for Homeland Security and Counterterrorism Lisa Monaco said in a statement. “The president authorized action at this time because it was the national security team’s assessment that these hostages were in danger with each passing day in ISIL custody.”

“The U.S. Government had what we believed was sufficient intelligence, and when the opportunity presented itself, the president authorized the Department of Defense to move aggressively to recover our citizens,” Monaco said in the statement. “Unfortunately, that mission was ultimately not successful because the hostages were not present.”

She added that “given the need to protect our military’s operational capabilities, we will not be able to reveal the details of this operation.”

“But the president could not be prouder of the U.S. forces who carried out this mission and the dedicated intelligence and diplomatic professionals who supported their efforts. Their effort should serve as another signal to those who would do us harm that  the United States will not tolerate the abduction of our people, and will spare no effort to secure the safety of our citizens and to hold their captors accountable.”

Foley’s news outlet, the Global Post, received an email a week ago from ISIS stating their intentions to execute the photojournalist.

“We received an email from the captors on Wednesday night of last week stating their intention to execute Jim,” Philip Balboni, president of the online news service, told a Boston Fox affiliate.

“The email was full of rage. We pleaded (to his captors) for mercy, but to no avail,” he added.

The White House knew of the email. It released the statement about the attempted rescue op hours after the news that ISIS gave warning of Foley’s execution.

In a Pentagon statement, press secretary Rear Adm. John Kirby said the operation “involved air and ground components and was focused on a particular captor network within ISIL.”

“As we have said repeatedly, the United States government is committed to the safety and well-being of its citizens, particularly those suffering in captivity. In this case, we put the best of the United States military in harms’ way to try and bring our citizens home,” Kirby said.

“The United States government uses the full breadth of our military, intelligence and diplomatic capabilities to bring people home whenever we can. The United States will not tolerate the abduction of our people, and will work tirelessly to secure the safety of our citizens and to hold their captors accountable.”

It has not been revealed exactly how many Western hostages are being held by ISIS, including journalists and aid workers.

At the end of the gruesome video of Foley’s murder, his executioner held journalist Steve Sotloff by the shirt and threatened to kill him next if Obama didn’t stop airstrikes against the caliphate.

At the State Department today, spokeswoman Marie Harf said they ”remain very deeply concerned” about Sotloff’s “safety and whereabouts.”

“Obviously, the intelligence community is looking to get anything they can to possibly use from this video,” Harf said. “Obviously I’m not going to outline what tactical military or intelligence options are at our disposal to respond here and don’t want to get ahead of any discussions in that regard. But we have the ability to hold people accountable for what they’ve done. We have reserved the right to take action to protect our people, including when our people have been harmed. The principle will guide what we do going forward.”

The U.S. military conducted an additional 14 strikes around Mosul dam today, she said.

When asked if any sort of rescue operation was in the works to get Sotloff, Harf replied, “I’m not ruling anything in or out specifically. I don’t — I’m not going to have more specifics to share with you right now on that.”

“But I just want to be very clear that we — no effort is spared in trying to bring our people home. While we can’t always talk about it publicly for obvious security and safety reasons of the remaining people being held, I just want to make very clear that we are taking and will continue taking steps.”

Foley’s parents appeared outside of their Rochester, N.H., home today to speak of their son — and the cruelty of his death.

“It’s horrific,” said John Foley. “People can die in lots of different ways but this was the most horrific and it haunts me how much pain he was in and how cruel this method of execution is.”

His parents learned of their son’s beheading at the same time everyone else did — when ISIS posted the video on YouTube and distributed the link widely on social media.

“It testified to his courage. He was courageous to the end and I think he accepted his situation and I think he accepted God’s faith in him and his faith in God,” John Foley said.

James Foley’s mother, Diane, stressed that her son was ”a great American and he believed in the very best of this country.”

She said they pleaded with Obama to rescue Sotloff, and she asked people to pray for the president.

“How long are we going to tolerate this?” John Foley said of the terrorists’ crimes.