The Obama administration was given multiple chances Wednesday to endorse a longtime ally’s airstrikes on America’s biggest enemy at the moment, the so-called Islamic State. Over and over again, Obama’s aides declined to back Egypt’s military operation against ISIS. It’s another sign of the growing strain between the United States and Egypt, once one of its closest friends in the Middle East.

This shouldn’t be a complete surprise; Cairo, after all, didn’t tell Washington about its strikes on the ISIS hotbed of Derna, Libya. Still, Wednesday's disconnect was jarring. White House Press Secretary Josh Earnest passed on a reporter’s question about an endorsement of Egypt’s growing campaign against ISIS. So did State Department spokeswoman Jen Psaki.

“We are neither condemning nor condoning” the Egyptian strikes, is all one U.S. official would tell The Daily Beast.

In other words, these once-close nations are now fighting separate campaigns against their mutual foe. And that could prove to be very good news for ISIS. The rift between U.S. and the region’s most populous country portends of another division that ISIS could exploit, this time for its expansion into northern Africa and the broader Middle East.

U.S. officials privately said they do not have a better idea for confronting the threat and the ongoing strains between the two nations has led to a breakdown of trust.

“The Egyptian military, in particular, is very frustrated with us,” one U.S. government official explained to The Daily Beast. “It is mutual frustration.”

At a briefing with reporters Wednesday, Navy Rear Adm. John Kirby called the relationship with Egypt “complicated.”

“We are constantly reviewing our relationship with Egypt,” Kirby said.

To the U.S., the ISIS threat may feel far away, in Iraq and Syria, where the U.S.-led air campaign is entering its seventh month. For Egypt, this is a danger that’s alarmingly close to home. ISIS is within its borders and in neighboring Libya. Extremist fighters have come from and travel through the Sinai. And many ISIS and jihadi fighters and weapons arrive in places like the Sinai from Libya.

Because of that, Egypt refused to join the 60-plus coalition formed last summer to confront ISIS. Instead, Egypt asked the U.S. for more weapons to confront its ISIS threat. But the U.S. has been largely hesitant, citing what it considers troubling political developments in Cairo. All the while, it appears ISIS has expanded its grip in the region.

On Monday, Egypt unilaterally launched an airstrike campaign on the restive Libyan city of Derna in response to a gruesome video showing the beheading of 21 Coptic Christian Egyptian workers along Libya’s shores in the city of Sirte.

Egypt did not inform the United States, its longtime ally, before the operation. And the United States stopped far short of backing Egypt’s effort. Rather, the U.S. called for a political solution in Libya, which is divided between two rival governments, each backed by different militias. Egypt’s call Wednesday for the United Nations to create a naval blockade to stop weapons transport to Libya was met with relative silence by the United States. And at the Pentagon, the military campaign against ISIS remains centered on Iraq and Syria.

Privately, some U.S. officials told The Daily Beast they worry that Egypt’s decision Monday to hit Libya—and its vows to do more—could do more harm than good. And yet they concede there is little they can do about it.

That the United States and Egypt are so at odds about the fight against ISIS is particularly striking, given the billions the U.S. has spent over four decades cultivating a relationship. Indeed, Egypt’s current president and nearly every military leader in the Egyptian army have received military training at a U.S. war college.

“After more $40 billion why is it we are not on a better page?” asks Amy Hawthorne, Rafik Hariri Center senior fellow at the Atlantic Council, who specializes on the Arab world, before answering her own question. “Simply because we have a close military relationship doesn’t mean we are going to be aligned on critical issues. [The aid] doesn’t buy agreement.”

The relationship arguably began to fray in 2003, when Egypt opposed the U.S. invasion of Iraq. Relations appeared to improve slightly in the run-up to the 2011 uprising known as the Arab Spring. The Egyptian military heeded U.S. calls that its troops should not shoot at protesters, for example. But since then, the relationship has soured, badly. Egypt held elections in 2012 only to oust the president, Mohammed Morsi, one year later amid nationwide protests. The U.S., at various points, backed both Morsi and his removal. The then-Minister of Defense, Abdel Fatah el Sissi, said at the time of Morsi’s ouster that he was carrying out the people’s will and had no political aspirations. A year later Sissi became president, prompting many in the U.S. government to call the leadership change undemocratic, even as Sissi won the post through an election.

At one point, some Obama administration officials suggested they no longer needed Egypt as they once did. But that was before the emergence of the self-proclaimed Islamic State.

In the last 18 months, tensions between Cairo and Washington have only mounted. The U.S. has suspended some weapons systems sales, like F-16 fighter jets, M1A1 Abrams tanks, and even spare parts for helicopters, in part because of how Sissi ascended to power. Meanwhile, Egypt has suppressed freedoms and made arms deals with China and France and hosted Russian President Vladimir Putin last week.

Last summer, when the United States began rallying for allies to join its coalition, Egypt asked instead for the United States to lift its suspension of weapons systems. But two government officials told The Daily Beast that Cairo did little to alleviate U.S. concerns about the current government. Egypt made the request while imprisoning activists, suppressing protests and even holding an American citizen, Mohammed Soltan, on spurious charges.

As an olive branch offering, the United States sent 10 Apaches to Egypt in December, calling them resources to conduct counterterrorism operations. But with no spare parts, those choppers are starting to breakdown. Sissi then began reaching out to other nations, including China and Russia, for weapons systems, as well as economic aid.

Sissi’s attack on Libya and his push to expand Egyptian relations beyond the U.S. has the backing of his population and the military. Egyptians demanded a reaction to the killing of its fellow citizens. And the strained relationship between the U.S. and Egypt is not lost on the public. The most common question Egyptians politicians, journalists and citizens alike have asked as their nation faced a mounting ISIS threat has been: “Where is the United States?”