Secretary of State John Kerry defended the decision two weeks ago to extend nuclear negotiations with Iran for up to seven months. (Carolyn Kaster/AP)

Secretary of State John F. Kerry predicted Sunday that a deal to limit Iran’s nuclear capacity could be reached in three or four months, or even sooner.

Appearing at the Saban Forum, which is affiliated with the Brookings Institution, Kerry defended the decision two weeks ago to extend nuclear negotiations with Iran for up to seven months. The extension came after the parties failed to agree on a comprehensive pact in last-minute talks leading up to a Nov. 24 deadline.

But Kerry said it will become apparent, long before the new June 30 deadline, if an agreement is feasible.

“We’re not looking at seven months,” Kerry said. “I think the target is three, four months, and hopefully even sooner if that is possible.”

Kerry’s hour-long speech at the forum — called “Stormy Seas: The United States and Israel in a Tumultuous Middle East” — was preceded by a heavy dose of skepticism from Israeli Prime Minister Benjamin Netanyahu, who spoke for 10 minutes on a video link from Jerusalem, which he called “the united capital of Israel.”

Netanyahu suggested Israeli opposition to a deal with Iran was a factor in the negotiations’ failure. Netanyahu lobbied hard against a deal, personally calling every foreign ministerfrom the countries negotiating with Iran, known as the P5+1, to outline his objections.

On Sunday, his words seemed to rebuke Kerry’s efforts to find a compromise with Iran.

“The Nov. 24 deadline has come and gone,” Netanyahu said. “That’s fortunate. Because a deal was not signed that would have left Iran as a threshold nuclear power. Though Israel isn’t part of the P5+1, our voice and our concerns played a critical role in preventing a bad deal.”

Netanyahu also seemed to signal his approval of a tactic urged by some members of Congress who want to add new U.S. sanctions on Iran, saying that painful economic measures would force Iran to abandon its nuclear ambitions. Iran denies it wants to enrich uranium for anything but peaceful measures, though many critics do not believe those assurances.

“Now we must use the time available to increase the pressure on Iran to dismantle its nuclear capability,” Netanyahu said without elaborating.

Kerry said preventing Iran from acquiring nuclear weapons has been at the center of President Obama’s foreign policy.

“We believe that the best way to prevent Iran from having a nuclear weapon is through a verified, negotiated agreement,” he said.

Kerry spoke at the same forum last year, right after the signing of an interim agreement that allowed formal negotiations to begin. Kerry seemed to relish recalling the premonitions of critics who proclaimed that Iran was bound to cheat and that the administration was jeopardizing national security.

Instead, Kerry argued, the world is a safer place. International inspectors have daily access to Iran’s enrichment facilities. Its stockpile of highly enriched uranium has been diluted or converted. And a plutonium reactor is effectively frozen.

“Now why are we doing this?” Kerry asked. “Because I believe, President Obama believes, the administration believes that it would be the height of irresponsibility, it would be against our own interests and those of our closest partners, to walk away from a table when and if a peaceful resolution might really be within reach.”

If negotiations succeed, he added, “the entire world — including Israel — will be safer for it.”