population that is more than 40 times as large. Washington lies about 10,000 kilometres away from Tehran -- well out of Iranian missile range -- compared with the roughly 1,500 kilometres between Tehran and Tel Aviv -- well within Iranian missile range. The U.S., the world's only superpower, is armed with an exponentially larger military, has the largest economy in the world, and wields much greater diplomatic clout. These drastically different parameters not only generate different perceptions of the Iranian threat, but also provide the U.S. with significantly more deterrence. Given these serious differences between the U.S. and Israel, only trust between the leaders can align their strategies to achieve the common goal of preventing an Iranian nuclear bomb. Mr. Obama and whoever will be elected Israeli prime minister in January must work to build the trust between them. Significantly, Israel has not asked the U.S. for a "green light" to attack Iran's nuclear sites. If necessary, and only as a last resort, Israel can attack alone. Yet, if Mr. Obama believes there's still time for diplomacy and sanctions to prevent Iran from being able to break out toward a nuclear weapon, Israel must trust the President and his pre-election commitments. Washington and Jerusalem would do well to work together to generate a new sense of trust. Major-General (ret.) Amos Yadlin is is Executive Director of the Institute for National Security Studies at Tel Aviv University and former head of military intelligence for the Israel Defence Forces. He will be