A $10bn arms deal is under discussion between the United States and its Arab and Israeli allies that will send a "very clear signal" to Iran, Chuck Hagel, the US defence secretary, has said.
Hagel, who is on his first visit to Israel as Pentagon chief, said on Sunday the US is committed to providing Israel's military with an advantage.
"The bottom line is that Iran is a threat, a real threat," Hagel said. "The Iranians must be prevented from developing that capacity to build a nuclear weapon and deliver it."
The first stop on Hagel's week-long Middle East trip came two days after the Pentagon said it was finalising a weapons deal to strengthen the militaries of Israel and two of Iran's key rivals, Saudi Arabia and the United Arab Emirates.
Al Jazeera's correspondent Simon McGregor-Wood, reporting from Jerusalem, said Hagel's visit was an opportunity to put controversies of the past behind, such as his earlier comments on Israel which affected his confirmation.
The deal includes the sale of KC-135 aerial refuelling tankers, anti-air defence missiles and tilt-rotor V-22 Osprey troop transport planes to Israel as well as the sale of 25 F-16 Fighting Falcon jets to the UAE.
The UAE and Saudi Arabia also would be allowed to purchase weapons with so-called "standoff" capabilities that enable them to engage the enemy with precision at a distance.
Every sovereign nation has the right to defend itself and protect itself
Asked if the arms deal sent a message that the military option was on the table if Tehran moved to build a nuclear weapon, Hagel said: "I don't think there's any question that that's another very clear signal to Iran."
Iran denies Western allegations that it is seeking to develop the capability to build nuclear weapons, saying its atomic activities are aimed at generating electricity.
Israel has repeatedly voiced its impatience with the pace of diplomatic efforts to curb Iran's enrichment of uranium, saying they should be coupled with a credible military threat.
Hagel, who faced resistance during his Senate confirmation hearing earlier this year from lawmakers who questioned his support for Israel, said part of the purpose of his visit was to underscore to Israelis that "the United States is committed to their security".
Asked about renewed debate in the Israeli media that Israel might have to strike Iran by itself, Hagel said "every sovereign nation has the right to defend itself and protect itself".
"Iran presents a threat in its nuclear programme and Israel will make the decisions that Israel must make to protect itself and defend itself," he said.
But Hagel added the US and other countries believe there is still time for diplomacy and tough international sanctions to have an impact.
After Israel, Hagel will visit Egypt, Jordan, Saudi Arabia and the United Arab Emirates.