(Bloomberg) — The fanfare and talk of history that surrounded this month’s decision by Israel and the United Arab Emirates to pursue peace quickly gave way to acrimony that’s testing the pact’s limits.

And as is often the case in the Middle East, the bone of contention is military superiority.

With the ink on the agreement barely dry, Israeli Prime Minister Benjamin Netanyahu and UAE officials were sparring over the Gulf nation’s long-standing request to buy the advanced Lockheed Martin Corp. F-35 jet from the U.S.

As the spat rumbled on Secretary of State Michael Pompeo, on a visit this week to both allies, attempted unsuccessfully to square the circle on a diplomatic achievement the Trump administration wants to stick as November’s election nears. Washington was firmly committed to selling advanced weaponry to the UAE, he said, while reassuring Israel it was committed to maintaining its qualitative combat edge in the region as stipulated under U.S. law. Netanyahu wasn’t convinced.

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Dan Shapiro, a former U.S. ambassador to Israel and visiting fellow at Tel Aviv University’s Institute for National Security Studies, said the thrust of the accord appeared to be clear: the UAE agreed to become just the third Arab state to normalize ties with the Jewish State; Israel suspended its plan to annex West Bank territory the Palestinians want for a state; and the U.S. would consider the UAE request for the F-35.

“It is difficult to impossible to imagine that Israel was unaware of that aspect of the agreement,” said Shapiro. “The UAE expects to receive something that they felt they were promised and if they don’t, it could affect the stability of the normalization.”

While he doesn’t expect the F-35 twist to collapse the pact, it could slow implementation.

That may already be happening. Axios reported that the UAE was disappointed enough over Netanyahu’s public opposition to the sale to cancel or postpone a meeting with U.S. and Israeli representatives at the United Nations last week.

History Lessons

A day earlier, the UAE Foreign Ministry said it had expected the U.S.-crafted accord to lead to “closer security cooperation among all three countries including on air defense and systems.”

Amos Gilad, a retired general and former Defense Ministry director of policy, said opposition to the jet purchase within Israel’s government, which already has the F-35 in its armory, stems from present military realities and lessons from history.

“The UAE has one of the best air forces in the Arab world. They do not need the creme de la creme of the F-35,” he said. “While in Israel, we have traditional concerns that anything you sell to one Arab country will be sold to another Arab country, and another Arab country, and we will find ourselves up against a potential coalition the moment potential political hurricanes hit.”

In the past, Israel has expressed concern to the U.S. when it comes to arms sales in the region, including local media reports that Israel lobbied against an F-35 sale to Turkey, a NATO ally of the U.S., in 2018. Turkey’s purchase last year of a Russian missile defense system may have doomed any future F-35 sale.

U.S. law requires that arms sales “to any country in the Middle East other than Israel” must not “adversely affect Israel’s qualitative military edge over military threats to Israel” and U.S. officials have said they remain committed to that. But the law doesn’t clarify what constitutes a legally defined adverse effect, according to a 2019 report by the Congressional Research Service.

Saudi Planes

Israel’s rapprochement with the UAE has been based largely on a shared distrust of Iran to which the U.S. is also party. But Israeli officials argue nothing is permanent in Middle Eastern diplomacy. Iran was an ally until the 1979 revolution yet is today considered Israel’s existential enemy. More recently, ties with Turkey have deteriorated during the long rule of President Recep Tayyip Erdogan.

The peace deal with the UAE evolved out of already informal ties between Israel and the Gulf Arab states as mutual concerns over Iran’s nuclear and regional ambitions grew.

UAE Minister of State for Foreign Affairs Anwar Gargash rejected the idea that the F-35 would be a reward for the UAE’s understanding with Israel.

The F-35 “has always been a target” to meet the UAE’s defense needs and has been requested for six years, Gargash told an Aug. 20 event with the Washington-based Atlantic Council. He said the UAE also is seeking to upgrade its Lockheed F-16 aircraft.

Amos Yadlin, a former head of military intelligence who now directs the INSS in Tel Aviv, said that the UAE’s proximity to Iran could make it easier for Iranian agencies to collect intelligence on the F-35, which has much-valued stealth capabilities.

Yet not everybody in Israel’s government is so worried.

”The debate around the F-35 is a non-issue” Energy Minister Yuval Steinitz said. “The plane doesn’t have the range to reach Israel from the UAE without two fuel tanks. This turns an advantage into a problem. I’m sure that there are many other things the Americans can do to insure Israel’s qualitative edge.”