"The U.S. must do everything it can to make certain that Iran does not get a nuclear weapon, that a nuclear Iran does not threaten Israel, and to prevent a nuclear arms race in the region. Sen. Sanders supports the agreement between the U.S., Iran, Britain, China, France, Germany and Russia regarding Iran’s nuclear weapons program, because it has the best chance of limiting Iran’s ability to produce a nuclear weapon, while avoiding yet another war in the region.
"While the agreement is not perfect, it is far better than the path we were on – with Iran developing nuclear weapons and the potential for military intervention by the U.S. and Israel growing greater by the day. If Iran does not live up to the agreement, sanctions can be reestablished and all other options remain on the table. It is incumbent upon us, however, to give the negotiated agreement a chance to succeed, and Sen. Sanders applauds President Obama and Secretary Kerry for their efforts."
Source: Candidate's Website 2015 https://berniesanders.com/issues/war-and-peace/