Israeli Prime Minister Benjamin Netanyahu has been one of the harshest critics the US-led framework deal with the Islamic Republic, which offers it sanctions relief in exchange for scaling back its contested nuclear program.
Israel considers a nuclear-armed Iran an existential threat, citing hostile Iranian rhetoric toward the Jewish state, Iran's missile capabilities and its support for violent militant groups. Iran says its nuclear program is for peaceful purposes.
"I say to every Israeli that today we have the ability to stop them if they decided to move quickly to a bomb and I absolutely guarantee that in the future we will have the ability to know what they are doing so that we can still stop them if they decided to move to a bomb," Kerry said.
Netanyahu believes the potential deal leaves intact too much of Iran's contested nuclear program, including research facilities and advanced centrifuges capable of enriching uranium, a key ingredient in building an atomic bomb.
Netanyahu's criticism has contributed to rising tensions between him and President Barack Obama.
"We think there needs to be a different deal, a better deal, and there are those that tell us this won't endanger Israel," Netanyahu said Sunday during a visit by US Sen. Rob Portman, R-Ohio. "I must say as prime minister of Israel, who is responsible for Israel's security this does endanger Israel.