Until January of this year, U.S. policymakers and American allies feared what Jordan’s King Abdullah II had dubbed the “Shia crescent.” The thinking was that as Iran’s power grew, this strategic alignment of hostile governments would stretch from the Islamic Republic of Iran, through its ally Syria, on to the newly empowered Shia majority in Iraq, and up to the shores of the eastern Mediterranean where it would reach Hezbollah in Lebanon. But that was before pro-American dictators started to fall like dominoes across the region. What we’re looking at now is what some, like historian Martin Kramer, have called a “Muslim Brotherhood crescent.”Take a look at the map. In last week’s Tunisian elections, the Islamist al-Nahda Party, once outlawed, won 90 out of 217 seats. As goes Tunisia, so goes the Arab Spring. In Libya, several Islamist figures, some of them reportedly aligned with al-Qaida, seem likely to fill the vacuum left by Muammar Qaddafi’s death. In Egypt, the Muslim Brotherhood, the region’s oldest Islamist movement, is prepared to compete for 50 percent of the country’s parliamentary seats in elections scheduled for later this month. The exact strength of the Islamist element in the ongoing Syrian uprising remains to be seen, but the contours of this new crescent are already becoming clear.An Islamist alliance drawn from the region’s Sunni majority spells a kind of long-term trouble for U.S. and Israeli interests that may be equally or even more dangerous than a Shia crescent—even if Iran gets a nuclear bomb. After all, the Shia crescent is sectarian by definition, which means that its transnational character actually enfeebles it. As most analysts recognize, if the clerical regime in Tehran comes tumbling down then all its regional assets will also be weakened, if not destroyed.That’s not true of a Muslim Brotherhood crescent, where the relative strength or weakness of Tunisian Islamists, for instance, has little bearing on the political power of Egypt’s Islamist movement. As University of Virginia professor Ahmed al-Rahim explains in a forthcoming issue of The Historical Review, “the Muslim Brotherhoods—from Morocco to Egypt to Iraq—have operated in practice as national Islamist organizations.” That is to say, the Muslim Brotherhood crescent is powerful because it both draws on the political aspirations of the regional Sunni majority and is deeply rooted in national sympathies.Parts of the West perceive this dangerous situation with a good deal of sangfroid. France, for instance, though it backed Tunisia’s former President Zine El Abidine Ben Ali when the uprising against him first began last January, now welcomes the Islamist triumph in its former colony. The election results are “tremendously good news,” said French Foreign Minister Alain Juppé. “After decades of disputable and disputed elections,” Juppé continued, “the ballot went ahead under excellent conditions: no notable incidents, and very high turnout by Tunisian voters.” So long as hundreds of thousands of Tunisian refugees don’t wash up on French shores, Paris would settle for Osama Bin Laden’s ghost as the country’s ruler.Washington’s position is a bit more complex. Even before the Arab Spring, the Obama Administration correctly believed that the Islamist movement was fast becoming one of the major powers in the region. The president’s advisers, including counterterrorism czar John Brennan, can be blamed for their enthusiasm in reaching out to outfits like Hezbollah, whose political program and intentions they misunderstood. But it was actually the Bush White House that set the precedent for reaching out to Islamists.In order to keep the peace in Iraq, the Bush Administration was compelled to make peace with—and buy off—local Sunni Islamists that shared the U.S. interest in defeating al-Qaida in Mesopotamia. Moreover, the Iraqi Prime Minister Nuri al-Maliki is from the Dawa party, a Shia Islamist organization co-founded by Hussein Fadlallah, the late spiritual leader of Hezbollah. Perhaps most significantly, despite the warnings of our Israeli and Palestinian allies, the Bush White House pushed for the Palestinian parliamentary elections in 2005 that brought Hamas to power.All the Obama Administration did was read the writing on the wall: Given a choice in free and fair elections, Arab electorates will invariably put Islamists in power. It is for this reason that the present White House has privileged its relationship with Turkey, and to a lesser extent Qatar, while it has downplayed its alliance with Israel. If the Islamists are riding a wave, the administration’s logic goes, then it is useful to have an Islamist as a go-between, like Turkish Prime Minister Recep Tayyip Erdogan. He is reportedly the world leader with whom Obama speaks most often after British Prime Minister David Cameron.Some argue that in spite of its anti-Israel and anti-Western rhetoric, Erdogan’s Freedom and Justice Party really is a model moderate Islamist organization. After all, there’s no ban on alcohol in Istanbul bars, and Turkish women aren’t compelled to wear the headscarf. Unfortunately, these domestic issues have virtually no bearing on vital U.S. interests. What should matter to U.S. policymakers is that Erdogan is the architect of an adventurist foreign policy and has promised to send warships to protect future aid flotillas. Erdogan, who uses anti-Israel rhetoric to stir the passions of the Arab masses, is no moderate, but a demagogue who has patterned his career after the modern Middle East’s most famous radical, Gamal Abdel Nasser.Indeed, “moderate” is a word that gets thrown around recklessly when it comes to the Islamist groups that comprise this new Muslim Brotherhood crescent. Consider the leader of al-Nahda, Rashid Ghannoushi, who, after many years of exile, may well be Tunisia’s next prime minister. He is routinely described as a moderate, even though he has praised the mothers of suicide bombers and believes that the “region will get rid of the germ of Israel.”Perhaps to better understand the term “moderate” we might consider Islamist parties in the context of how they exercise power in their local environments. Where Osama Bin Laden spoke of a revived caliphate that would unite the umma, Islamists like Ghannoushi, Erdogan, and the Muslim Brotherhood are focused on their own national projects. Extremist Islamist outfits like Bin Laden’s original al-Qaida live in caves and rely on the support of Middle Eastern governments in order to accomplish operations like blowing up planes. So-called moderate Islamist parties, on the other hand, win electoral contests that leave them in charge of Middle Eastern governments, security services, and militaries with artillery, tanks, air forces, and navies.Despite their name, the moderates are more dangerous than the extremists by a matter of magnitude. It’s no wonder the Obama Administration seeks to appease them by keeping Israel at arm’s length.Lee Smith is the author of The Consequences of Syria.