As a result of the recent agreement on Iran's nuclear program, over the next 15 years Iran will refrain from enriching or acquiring materials such as uranium or plutonium for use in nuclear weapons. In exchange, the United Nations Security Council, Europe and the United States will begin to lift the sanctions currently in place against Iran.
However, the accord still leaves room for Iran to emerge as a nuclear threshold power over the long term. Israel's continued opposition to the agreement is thus not unfounded.
Another rival in the region, Saudi Arabia, is also privately less than sanguine about the new detente between the U.S. and Iran. Ever since the establishment of the Shiite regime in Iraq, the opposition of Sunni Iraqis has intensified, putting the country well on its way to becoming a failed state. This also means the gradual loss of Iraq's function as a "buffer zone" between the predominantly Shiite Iran and the overwhelmingly Sunni Saudi Arabia. Indeed, what's currently unfolding in Yemen is a proxy war between those two powers.