U.S. Secretary of State John Kerry says Iran is "forever forbidden from building a nuclear weapon."
In February 25 comments at a hearing of the House Foreign Relations Committee in Washington, Kerry sought to allay concerns about Iran's controversial nuclear program ahead of a possible agreement to curb it in exchange for easing sanctions against Tehran.
Kerry said Iran's membership in the Nonproliferation Treaty (NPT) prevents Tehran from possessing nuclear weapons.
Iran is a signatory to the NPT agreement but has already been found in noncompliance for failing to declare its uranium-enrichment program.
Israeli Prime Minister Benjamin Netanyahu, who has repeatedly claimed Iran is seeking to develop nuclear arms and opposes easing sanctions on Tehran, has accused world powers that they "have given up" on trying to stop the Islamic republic from obtaining nuclear weapons.
But Kerry questioned Netanyahu's position, saying that he "may have a judgment that just may not be correct."
Netanyahu is due to address the U.S. Congress next week to argue Tehran is not negotiating in good faith.
U.S. national security adviser Susan Rice said on February 25 that Netanyahu's visit is "destructive" to U.S.-Israeli relations.