TEL AVIV  — U.S. Defense Secretary Chuck Hagel said on Sunday a $10 billion arms deal planned with Arab and Israeli allies sent a "very clear signal" to Iran that military options remain on the table over its nuclear program.

"The bottom line is that Iran is a threat, a real threat," Hagel, who arrived in Israel on Sunday on his first visit there as defense secretary, told reporters on his plane.

"The Iranians must be prevented from developing that capacity to build a nuclear weapon and deliver it," he said.

Hagel was due to meet Israeli Defense Minister Moshe Yaalon on Monday and Prime Minister Benjamin Netanyahu on Tuesday, with little progress reported at talks this month between Iran and world powers.

The first stop on Hagel's week-long Middle East trip came two days after the Pentagon said it was finalizing a deal to strengthen the militaries of Israel and two of Iran's key rivals — Saudi Arabia and the United Arab Emirates.

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The deal includes the sale of KC-135 aerial refueling tankers, anti-air defense 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 would also be allowed to purchase weapons with so-called "stand-off" capabilities enabling them to engage an enemy with precision at a distance.

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."

But he added the military option had been "very clear to Iran for some time" and said the arms deal was a continuation of U.S. policy to maintain Israel's so-called "qualitative military edge" in the region, a general reference to the supply of advanced U.S.-made weaponry and technology to the Jewish state.

Iran denies Western allegations it is seeking to build nuclear arms, saying its efforts aim at electricity generation.

Israel, widely believed to be the Middle East's only nuclear power, has repeatedly voiced impatience with diplomatic efforts to curb Iran's enrichment of uranium, saying they should be coupled with a credible military threat.

Both Israel and the United States have said all options remain on the table for dealing with any nuclear threat.

Hagel, who faced resistance during his Senate confirmation hearing this year from lawmakers who questioned his support for Israel, said part of the purpose of his visit was to reassure Israelis "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 program and Israel will make the decisions that Israel must make to protect itself and defend itself," he said.

But Hagel added the United States and other countries believe there is still time for diplomacy and tough international sanctions to have an impact.

"The military option is one option that remains on the table, must remain on the table," he said. "But military options, I think most of us feel, should be the last option."

After Israel, Hagel will visit Egypt, Jordan, Saudi Arabia and the United Arab Emirates. His trip comes amid concerns about regional stability due to Iran's nuclear program, the rocky transition to civilian rule in Egypt and civil war in Syria.