U.S. Defense Secretary Chuck Hagel says the U.S. and Israel need to ensure that their alliance is "closer than ever," as Mideast security challenges grow more complicated.

Hagel spoke briefly before starting a closed-door meeting Tuesday with Israeli Prime Minister Benjamin Netanyahu.

In his remarks, Netanyahu thanked the Obama administration for deepening ties over the past four years. And he said he appreciates the administration's recent statements in support of Israel's determination to do whatever is necessary to stop Iran from becoming a nuclear power.

Netanyahu said Iran's nuclear ambitions and its arming of terrorists are developments Israel "cannot accept."

Hagel was wrapping up a three-day visit to Israel and was heading to Jordan to consult with government officials. Later Tuesday he was to fly to Saudi Arabia.