Speaking to the U.S. House Intelligence Committee in a hearing on Thursday, Comey said that his agency’s ongoing battle with Apple over privacy is “the hardest question I’ve seen in government,” according to CBS News, which obtained a transcript of his comments. He added that the only way forward is to engage in “conversation and negotiation” to find a proper balance between security and privacy.

Comey didn’t explain why the balance between privacy and encryption is the “hardest question” he’s seen yet, but he warned that it could ultimately create a less-secure country.

Comey’s comments come on the heels of Apple (AAPL) CEO Tim Cook’s first public interview about his company’s row with the FBI over iPhone encryption. Speaking to ABC News on Wednesday, Cook said that allowing the FBI to access the phone used by San Bernardino attacker Syed Farook could create a dangerous precedent that would hurt all Americans.

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“This would be bad for America,” Cook told ABC News. “It would also set a precedent that I think many people in America would be offended by and when you think about those, which are known, compared to something that might be there, I believe we are making the right choice.”

The comments come more than a week after a U.S. magistrate judge ordered Apple to work with the FBI to provide software that would allow law-enforcement officials to break the iPhone’s passcode and gain access to its data. The FBI, citing the All Writs Act signed into law in 1789, has argued that the data could be critical in bringing justice to the victims.

“Fourteen people were slaughtered and many more had their lives and bodies ruined,” Comey wrote in an open letter earlier this week. “We owe them a thorough and professional investigation under law. That’s what this is. The American people should expect nothing less from the FBI.”

Apple’s Tim Cook Says the iPhone Encryption Debate Should Shift to Congress

Comey added that his agency was simply asking for access to a single device and that it doesn’t “want to break anyone’s encryption or set a master key loose on the land.”

Despite those claims, Cook and his allies have continued to rail against the ruling and the FBI, saying that Apple is standing up not only for its own rights, but for those of all Americans. Indeed, Cook has called the FBI’s request “an overreach” that could create “a dangerous precedent” if the government’s demands are met.

In his interview with ABC News, Cook again stood his ground, calling the FBI’s request “the software equivalent of cancer.” He added that he would be willing to take the case to the U.S. Supreme Court. He has previously said he hopes that the case will ultimately be thrown out in favor of a commission of private and public sector representatives that would work together to solve the issue.

Comey, who has long been critical of encryption, told the House Intelligence Committee on Thursday that he’s not against negotiations with Apple and others, but believes that the American people don’t fully understand “the cost associated with universal strong encryption.” He suggested, according to CBS News, that losing the ability to access data will only hurt law enforcement’s ability to find and thwart illegal activity—a claim he has made on several occasions in the past and one that Apple and other technology companies have brushed aside.

The case between Apple and the FBI may indeed be one that continues all the way to the Supreme Court. But first, Apple must file its response to the court on Friday. Apple is expected to decline the request, potentially leading to a protracted court case.