The United States is deploying defensive missile batteries:
The US is dispatching Patriot defensive missiles to four countries – Qatar, United Arab Emirates, Bahrain and Kuwait – and keeping two ships in the Gulf capable of shooting down Iranian missiles. Washington is also helping Saudi Arabia develop a force to protect its oil installations.
[...] An unnamed senior administration official told the New York Times: "Our first goal is to deter the Iranians. A second is to reassure the Arab states, so they don't feel they have to go nuclear themselves. But there is certainly an element of calming the Israelis as well."
We are now tacitly playing a game of nuclear chicken. An Iran with nuclear weapons tips the balance of power clearly in their favor, potentially casting a wide net across many middle eastern states. The United States is probably doing its best to prevent the Saudis and other oil-rich nations from purchasing their own nukes from a willing seller (Russia?). Once more into the abyss, of nuclear brinksmanship.