The tension between Cairo and Riyadh due to the daylight between their threat perceptions is no secret. King Salman of Saudi Arabia prioritizes halting the rise of Iran, while Egyptian President Abdel Fattah al-Sisi seeks to vanquish the Islamists and maintain regional regime stability. These clashing priorities came to the fore in two of the region’s most violent civil wars, in Syria and Yemen, where the two allies found themselves misaligned.This turn of events was particularly disappointing for the Saudis, who had invested tens of billions of dollars in keeping the Egyptian military regime afloat since 2013, but saw their investment translate into very little support on the battlefield in the fights that mattered to them. Similarly, the Saudis plan to continue purchasing billions of dollars in US arms and munitions, which will be a boon to the defense industry (and hence help President Donald Trump fulfill his promises to protect US industry).But their optimism about Trump could give way to disappointment once more if they expect Washington to reciprocate with an interventionist anti-Iran US foreign policy: thus far, Trump’s foreign policy appears more in-line with Sisi than Salman.In Syria, Saudi Arabia staunchly opposed the Assad regime because of its close ties with Riyadh’s arch-nemesis, Iran. The popular uprising against Damascus presented it with an opportunity to support the overthrow of an unfriendly regime and potentially replace it with an ally, while simultaneously weakening Iran’s Hezbollah proxy in Lebanon.In addition, the Alawite Assad regime’s brutality against the majority Sunni population offered the Saudis the chance to present themselves as the supporters and defenders of the Sunni world. Chasing after these opportunities led Riyadh into murky territory in which it was overly permissive about giving support to Islamist rebel groups with radical orientations, including Jabhat al-Nusra.Despite the billions of dollars in aid that he received from the Gulf, Sisi was not quite as gung ho as his benefactors about regime change in Syria. Having witnessed the Arab Spring from a military-intelligence vantage point, he is well aware of the interconnectedness of the Arab states and that it was the successful revolt against Ben Ali in Tunisia that inspired citizens in Mubarak’s Egypt, Saleh’s Yemen, and Assad’s Syria to rise up. With this in mind, President Sisi is right to think that the fall of the Assad regime in Damascus could lend fuel to the burning insurgency against him.Thus it is no wonder that the Egyptian autocrat expressed support for Assad in saying, “Our priority is to support national armies, for example in Libya...The same with Syria and Iraq.” Also, Sisi is undoubtedly concerned by the cooperation between the Islamic State in Syria and the Islamic State Sinai Province and at least partially attributes the Egyptian branch’s increased lethality to the partnership. Therefore, he stands to lose far more in pushing for the collapse of the Assad regime, which could result in increased ungoverned space that is vulnerable to exploitation by Sinai Province’s senior partner than he stands to gain by rolling back Iran and its allies, which pose no comparable domestic threat to him.In Yemen, the Saudi-led coalition launched a campaign nearly two years ago to push back on the Iranian-backed Houthi advances that forced the Hadi government into exile. While some of the alliances on the Yemeni battlefield are pragmatic in nature, for example the cooperation between former nemeses Ali Abdullah Saleh and the Houthis, the Saudi-led pro-Hadi coalition capitalized on the ideological distaste that Muslim Brotherhood offshoot al-Islah had for the Zaydi Shi’ite Houthi movement and recruited it join the coalition’s ranks.The cooperation with Islah is part of a growing trend: Since King Salman rose to power in 2015, the oil kingdom has taken a more conciliatory approach to the Muslim Brothers in order to bolster its coalition against Iran. It is also worth noting that if the Houthis’ rise created conditions conducive for al-Qaida in the Arabian Peninsula to expand, the Saudi-led coalition’s campaign has allowed it to thrive in a mutually beneficial relationship in which the coalition forces and AQAP fight against Houthi control.In light of Sisi’s hostile relationship with the Muslim Brotherhood, as the organization sought to undermine his control of the state, he was less than enthralled with the prospect of participating in a campaign to empower its affiliate in Yemen.From Sisi’s perspective, the Islamist nature of groups that Saudi Arabia is cooperating with makes them more dangerous than the Houthis and their loose ties to Iran – considering the direct threat that Egyptian Islamists pose to the Sisi regime – while Tehran or the 1% of the Egypt population that is Shi’ite poses no comparable danger.This distaste for participation in the war in Yemen is probably only magnified by Egypt’s traumatic national memories from Nasser’s adventurism there in the 1960s, which resulted in the deaths of tens of thousands of Egyptian soldiers. Needless to say, the Saudis were disappointed by Egypt’s mere symbolic contribution to the war to defend its benefactors’ southern border from crossborder attacks and ballistic missiles.In both Syria and Yemen, Trump’s initial policies and statements appear to be more in-line with Cairo than Riyadh. The president has noted that he does not seek regime change in Damascus, has expressed interest in cooperation with Moscow in Syria despite its pro-Assad stance, and appears more focused on eradicating Sunni terrorism “from the face of the Earth” than rolling back Iran.In Yemen, the US’s latest involvement in the civil war is hardly what the Saudis would have hoped for and could even work to their detriment. Instead of fighting the Iranian-backed Houthis, the US is launching attacks on AQAP, which is fighting against the Houthis. Riyadh may be relieved that the Trump administration will likely sell it weapons without any of the trouble that the Obama administration gave it about human rights, but if it is hoping that big-ticket weapons contracts will push the US to fight Iranian interference in Syria and Yemen, it might be disappointed once again.The writer is special assistant to the director of Israel’s Institute for National Security Studies.