US President Donald Trump’s decision to recognize Jerusalem as the capital of Israel confirms Abba Eban’s aphorism that “men and nations behave wisely once they have exhausted all other alternatives.” Indeed, one must be puzzled by the reasoning behind this announcement, which, according to Trump, serves America’s best interests.The multiple reports published by the media in the aftermath of Trump’s declaration focused on two things: first, Trump’s desire to appease the Evangelists and/or Jews in the US; and second, his desire to honor his election campaign promise to declare Jerusalem Israel’s capital. He rationalized the decision by claiming that a new approach was required since all the other avenues were exhausted.But these two reasons do not appear to be sufficient to trigger such a drastic statement, especially one that stands in contrast to American interests, or to Israel’s interests, in fact. Thus, one may wonder if it was not Trump’s concern for his dignity and his ego, rather than diplomatic logic or foreign policy strategy, that served as the main catalyst for the decision.Trump’s decision harms US interests in several ways. One, in contrast to his desire to portray America as an honest broker in the Israeli-Palestinian conflict, Trump identified himself completely with one side – Israel. Although he qualified his statement by saying that this decision does not define the boundaries of Jerusalem, the content and tone of his speech was clearly one-sided. An even-handed mediator should have presented a corresponding or equivalent concession to the other party. As a result, the Palestinians will be highly suspicious of any new peace plan that the US attempts to present.Two, the decision will unite Arabs and Muslims against the US. Trump worked very hard to reconcile with the Saudis following president Barack Obama’s foreign policy debacle, and he probably coordinated the declaration with moderate Arab leaders, but popular opposition across the Arab and Islamic worlds could influence the position of friendly Arab regimes. Jerusalem and the Palestinian issue are the lowest common denominators in the Arab world, and are still able to trigger charged public reactions. Although these may subside after a while, the ominous implications of Trump’s decision will last, at least as long as he remains in power.Three, the decision opened two unnecessary fronts for the US – one in the UN, and the other with the EU, where most countries oppose Israel’s occupation and control of east Jerusalem.Four, the consequent tension between the US and the moderate Arab countries, on the one hand, and between the US and Europe, on the other, serves the interests of Iran and its Middle East proxies, which can be counted on to exploit the opportunity to inflame their public opinion against the US and Israel. Turkish President Recep Tayyip Erdogan and Russian President Vladimir Putin will no doubt attempt to use the opportunity to improve their own positions and influence.Five, the decision will exacerbate the divisions between the various American agencies (particularly between the White House and State Department) and between them and the public, who oppose the move.And, finally, the possibility of a violent confrontation in the Middle East or elsewhere as a result of the decision should not be underestimated.If Trump’s announcement turns out to be part of a grand plan he is cooking up behind the scenes, Israel will be forced to reciprocate and make a corresponding concession to the Palestinians. So far, Prime Minister Benjamin Netanyahu has not expressed any intention of moving forward in the peace process. Even if he had, the composition of his government would not allow any significant move.This is unfortunate, because the post-Arab Spring situation in the Middle East offers an opportunity to strike a deal with the Palestinians, with the support of several moderate Arab countries, based on a modified version of the Arab Peace Initiative. It is still not clear whether the Palestinians are ready, but a generous Israeli offer, backed the US and those Arab countries, might draw them to the negotiating table. At present, after Trump’s declaration the likelihood of a breakthrough in the conflict looks even more remote than ever. The inevitable conclusion is that Trump’s decision recalls both Eban’s euphemism and Barbara Tuchman’s march of folly theory – that governments pursue policies contrary to their own interests.The author teaches at the Department of Islamic and Middle East Studies of the Hebrew University of Jerusalem and is a board member of Mitvim – the Israeli Institute for Regional Foreign Policies.