Barack Obama on Wednesday arrived in Israel for the first time as president, vowing an "eternal" alliance with the Jewish state as it faces Iran's nuclear threat and perilous change in the Middle East.
Obama strove for reassurance as he faces scepticism over his strategy for confronting Iran and his personal commitment to Israel, following sharp public disagreements with Prime Minister Benjamin Netanyahu.
"The United States is proud to stand with you as your strongest ally and your greatest friend," Obama said at a lavish welcoming ceremony, shortly after Air Force One rolled to a halt to a peal of military trumpets at Tel Aviv's Ben Gurion airport.
"Our alliance is eternal, it is for ever," Obama declared, arguing America's vital national security interests mandated a strong defence of Israel, which he said "makes us both stronger."
Obama's arrival, on a visit more likely to be marked by symbolism and his homage to the ancient roots of the Jewish state than progress on the Israeli-Palestinian conflict, sparked glowing praise from Israeli leaders.
President Shimon Peres lauded Obama as a "remarkable world leader" who had shown a deep personal commitment to protect Israel, taking implicit aim at a perception the US president is not sufficiently warm to the Jewish state.
"A world without your friendship would invite aggression against Israel... In times of peace, in times of war, your support for Israel is unshakeable," he said.
Netanyahu was also effusive as Obama embarked on the first overseas mission of his second term, which will also see him hold talks with Palestinian president Mahmud Abbas in Ramallah and on Friday travel to Jordan to meet King Abdullah II.
"Thank you, Mr President, for upholding the Jewish people's right for a Jewish state in our homeland and for boldly defending that right in the United Nations," Netanyahu said.
For all the rhetoric, officials have downplayed expectations for Obama's long-awaited visit, and there are few hopes his arrival will overcome the deadlock in Israeli-Palestinian peace efforts.
"Peace must come to the Holy Land," Obama told his hosts on arrival but he has made clear he was coming to listen rather than launch any new peace initiative.
Disillusioned by the failure of Obama's first-term peace efforts, the Palestinians are hoping he will help broker the release of more than 1,000 prisoners held by Israel and also free up $700 million in blocked US aid.
Obama will tell the Palestinians that initiatives like seeking statehood recognition at the United Nations are counterproductive, while warning Israel that settlement building undercuts the chances of resuming peace talks.
But peace negotiator Nabil Shaath on Wednesday said Obama had disappointed Palestinians who once warmed to his calls for an end to settlement building.
"President Obama appeared to give up on his goal," Shaath wrote in Haaretz newspaper, mourning 1,000 Palestinian deaths in violence over the past four years.
"We could have saved lives and political capital if President Obama had shown the determination to create the right environment for meaningful decisions leading to a two-state solution."
After the welcome ceremony, the US leader came face-to-face with Israel's preoccupation with security, visiting a mobile battery of the US-funded Iron Dome missile defence system.
He then boarded his Marine One helicopter which flew him to Jerusalem where he is to meet Peres at 1400 GMT before having talks and then dinner with the Israeli premier with the focus likely to be on Iran.
It seems unlikely Obama and Netanyahu will narrow their differences over the point of no return on Iran's nuclear programme.
Obama has said Iran will not be able to build a nuclear weapon for "over a year or so."
But Netanyahu says Iran could have the capacity to produce a bomb much earlier, within months, and questions whether sanctions will change Tehran's calculations.
During his visit, Obama will pointedly court the historic symbolism of the Jewish State when he inspects the Dead Sea Scrolls and visits the tomb of Theodor Herzl, founder of modern Zionism.
The choreography is intended to show Israelis, Arabs and political foes back home that Obama is deeply committed to Israel's security and future, despite some scepticism about his motives.
He is on tricky political ground: a survey by the independent Israel Democracy Institute showed that while 51 percent of Jewish Israelis considered Obama neutral toward Israel, 53.5 percent did not trust him with Israel's vital interests.
A major part of the charm offensive will be on Thursday when Obama delivers a speech to hundreds of young Israelis.