On January 31, Egypt became the first Arab country to declare Hamas’s armed wing a terrorist organization. In so doing, Egypt aligned itself with America and the European Union, both of which have long deemed Hamas a terrorist group (the EU is currently appealing a December court ruling overturning its designation). Cairo is also fully engaged in the West’s battle against the Islamic State, though it’s focusing on the group’s Sinai-based affiliate, Ansar Bayt al-Maqdis. All this begs an obvious question: Why does Egyptian President Abdel-Fattah al-Sisi seem to be the West’s least favorite Arab leader?Granted, he’s an autocrat who brutally suppresses dissent, but so is every other Arab leader – and the West seems prepared to overlook their repression as long as it deems them sufficiently opposed to Islamist terror. Thus Western leaders flocked to Saudi King Abdullah’s funeral last month, though Saudi Arabia is one of the world’s most repressive countries, where women are forbidden to drive and bloggers can be sentenced to 1,000 lashes. And Palestinian Authority President Mahmoud Abbas is feted in every Western capital, though he’s now in the eleventh year of his four-year term and his security forces routinely arrest and intimidate journalists.Sisi, in contrast, has long received a cold shoulder. Congress froze American aid to Egypt after he took power in2013, finally lifting this ban only two months ago; thus he’s had to rely on the Gulf States and Russia for desperately needed military and financial aid. He has yet to visit Washington, though he did meet President Barack Obama at the UN in New York in September; in contrast, the State Department recently hosted officials from the Muslim Brotherhood, Sisi’s bitterest opponent. And his European trip in November didn’t include the key European capitals of Berlin and London. So here’s my theory: The West dislikes Sisi’s war on terror because, unlike that of other Arab countries, it threatens the logic of one of the West’s most cherished policy goals – an Israeli withdrawal from the West Bank.Hamas has abetted Sinai jihadists since long before Sisi took power; after a deadly attack in August 2012, for instance, Cairo accused three Hamas members of involvement and demanded their extradition from Gaza. But Sisi escalated the battle against Gaza-based terror dramatically. Last March, an Egyptian court banned Hamas activities in Egypt; in October, Egypt began razing hundreds of houses along the Gaza border to create a buffer zone to stem cross-border traffic in weapons and terrorists; and now, it has declared Hamas a terrorist organization.Yet while Western countries also ostensibly oppose Hamas, Sisi’s war poses two problems for them. First, it refutes their fond fantasy that Palestinian terrorists are merely anti-Israel, and would abandon terror if Israel just “ended the occupation.” A group that’s been exporting mayhem to a neighboring Arab country for years won’t stop just because Israel cedes more territory.More importantly, however, it refutes the very idea that further Israeli withdrawals would promote Mideast stability – because in fact, Israel’s 2005 pullout from Gaza was the direct cause of Sinai’s radicalization. Until 2005, Israeli troops controlled the Gaza-Egypt border, limiting contact between Hamas and Sinai. But when the IDF left, that restraining influence disappeared. And the impact, as journalist Ehud Yaari noted in a 2012 study, was devastating:As Bedouin political activist Ashraf al-Anani put it, “a fireball started rolling into the peninsula.” Illegal trade and arms smuggling volumes rose to new records, and ever-larger sectors of the northern Sinai population became linked to Gaza and fell under the political and ideological influence of Hamas and its ilk ... In short, despite then Prime Minister Ariel Sharon’s quiet hope that Cairo would assume unofficial responsibility for Gaza affairs, the Israeli withdrawal instead allowed Hamas to export its influence into Egyptian territory.Facilitated by the dramatic increase in the number of tunnels ... the expansion of Hamas and other Palestinian activities in the Sinai was unprecedented. In fact, the arms flow was often reversed, with weapons going from Gaza to the Sinai. During the [Egyptian] revolution, for example, observers noted a huge demand for firearms in the peninsula…Today, a significant number of Hamas military operatives are permanently stationed in the Sinai, serving as recruiters, couriers, and propagators of the Hamas platform. A solid network of the group’s contact men, safe houses, and armories covers much of the peninsula … In addition, Hamas, Palestinian Islamic Jihad, and other factions have been moving some of their explosives workshops—which produce homemade missiles, rockets, mortars, improvised explosive devices, and so forth—from Gaza to the Sinai in recent months.Nor was it just arms and ideology that Gaza exported to Sinai: According to Israeli intelligence, Palestinian terrorists also trained their Sinai counterparts – and jihadists from other countries as well.“We thought Sinai was the source of all evil for Gaza, but it turned out that things were exactly the opposite,” a senior intelligence official told Haaretz in 2013. “We thought experienced global jihad operatives from Afghanistan and Iraq would come to Sinai, and from there to Gaza, but in practice, the operatives from Gaza are the ones who taught the operatives in Sinai everything they know.”It doesn’t take an Einstein to realize that just as Israel’s departure from Gaza allowed Hamas free rein to destabilize neighboring Sinai, Israel’s departure from the West Bank would give it free rein to destabilize neighboring Jordan. True, the West Bank is currently controlled by Abbas, not Hamas. But so was Gaza when Israel left – until Hamas staged a military coup two years later. Would anyone seriously bet against a similar coup in the West Bank once the IDF, the main force keeping Hamas in check, was gone? Thus Sisi’s war on both the Sinai jihadists and Hamas is a constant and none-too-subtle reminder that far from being stabilizing, an Israeli pullout from the West Bank would be deeply destabilizing. Yet after years of declaring such a pullout to be a top foreign policy priority, Western leaders don’t want to face this unpleasant truth. So instead, they’ve taken the easier route: simply shunning the man whose policies keep bringing it to mind. Evelyn Gordon is a journalist and commentator. Follow her on twitter here.