During the past two years, Iran and Israel have traded missile and air strikes three times, and by now, war between them is old news. War between Iran and the Gulf Arab states of Saudi Arabia, Qatar, Kuwait, Bahrain, and the United Arab Emirates, however, is something new. According to reports, Iran fired missiles at all of them this morning. This video appears to show an attack on Juffair, the area of Bahrain that hosts the U.S. Navy’s Fifth Fleet. Similar attacks were reported in the other countries, all of which host American bases or other strategic interests.All these countries, with the possible exception of the U.A.E., have been at various times torn about whether to treat Iran like a bad neighbor who must be tolerated, or a bad neighbor whose house needs to be burned down with the neighbor in it. This morning, after the attacks, Saudi Arabia’s foreign ministry issued a statement condemning Iran’s “cowardly” attacks, and noting that the attacks had come even though Saudi Arabia had declined to let its airspace be used in an operation against Iran. Saudi Arabia had opposed the war. Iran’s strikes “cannot be justified in any way,” the statement said. Other targeted countries issued similar condemnations. Together they leave little doubt that the countries have moved away from the camp of “strongly worded letter to the homeowners’ association” and toward the camp of arson. These countries once wondered whether Iran could be appeased and contained. Now they do not.The Saudis in particular have viewed the Iranian regime as a menace that must be abided. Crown Prince Mohammed bin Salman, in his 2022 interview with me, made clear that he viewed other Arab Gulf states as family, and that families fight but eventually make up. Iran was in a different category. If its government, which has an unbroken record of hostility toward Riyadh, could be toppled, then it should be—but in the meantime, deals would have to be made, and concessions granted.In 2022, Iranian proxies launched a drone-and-missile attack against Abu Dhabi, the capital of the U.A.E. It killed three people and conveyed to the U.A.E.’s leaders that they would need to take Iran’s views into account as they explored deepening relations with the United States and Israel. The American response to this attack was not swift. Three weeks later, American F-22s arrived, with other military hardware meant to deter Iran and defend against another attack. The Emiratis counted those intervening defenseless days and decided that the response was worryingly slow—so slow that they needed to hedge their bets, in case the United States would hesitate even longer to defend them if attacks became more serious. They pulled out of a major maritime-security arrangement with the United States the next year.Bahrain is probably the Sunni monarchy that has felt its existence most acutely menaced by Iran. Iran has tried to topple the king there at least three times.None of these Arab autocracies wanted to choose between Iran and the United States. But one factor made the decision easier, and a second made it inevitable. The first was the Trump administration’s signaling, publicly and privately, that it would end the Islamic Republic with or without the Gulf’s support, and that it would support the Gulf states fully and immediately if Iran attacked them. The second, of course, was the Iranians’ decision to attack them as their first reaction to the American strikes.A luxury hotel is now in flames in Dubai. Attacking a five-star resort in Dubai is like attacking a boulangerie in Paris, or a football match in London, or a Black Friday stampede at a Walmart on Long Island. It is an assault on something nationally iconic, and for the nation hit, it has a way of clarifying distinctions that have long been muddled.