JERUSALEM — Defense Secretary Chuck Hagel arrived in Israel on Sunday to put the finishing touches on a complicated $10 billion arms deal with three Middle Eastern countries, saying the pact sends “a very clear signal” to Iran.

Under preliminary terms of the agreement, the United States would sell tilt-rotor V-22 Osprey aircraft — which can take off like a helicopter but cruise at airplane speed — to Israel. It would be the first time the Pentagon has approved a foreign sale of the Osprey, which can carry combat troops and are prized for their maneuverability.

The United States also would provide Israel with KC-135 refueling planes, which could extend the range of Israeli fighters and bombers so that they could be used for an attack on a country like Iran. Israel also would acquire advanced missiles for its warplanes.

Hagel has visited Israel several times previously, including during his 12 years as a Republican senator from Nebraska, but this is his first visit since he became defense secretary in February. Hagel was narrowly confirmed by the Senate after some pro-Israel groups vigorously opposed his nomination, arguing that he was insufficiently supportive of the Jewish state and too soft on Iran.

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Speaking to reporters aboard his military aircraft, Hagel took pains to emphasize that the United States and Israel both regard Iran as a clear threat that must be prevented from developing nuclear weapons. He emphasized Israel’s right to self-defense and repeated that the Obama administration would not rule out military action to stop Iran from building nuclear bombs.

But Hagel acknowledged that the Obama administration and Israel do not share the same assessments about how close Iran is to developing nuclear weapons and whether international sanctions and diplomacy can be successful.

“When you back down into the specifics of the timing of when and if Iran decides to pursue a nuclear weapon, there may well be some differences,” he said.

Hagel is scheduled to meet with other Israeli leaders Monday and Tuesday, including Prime Minister Benjamin Netanyahu.

Israel is the first stop for Hagel on a Middle East journey that also will take him to four Arab countries: Jordan, Egypt, Saudi Arabia and the United Arab Emirates.

Saudi Arabia and the U.A.E. are the other two countries negotiating the $10 billion arms deal. The U.A.E. is seeking to buy 25 F-15 fighter jets and other weapons, while Saudi Arabia wants advanced missiles to equip a $30 billion fleet of F-16 aircraft that it bought from the United States in 2010.