US President Barack Obama has arrived in Israel for his first trip there since he was elected, amid protests and tight security in Israel and the Palestinian territories.
In a welcoming ceremony at Tel Aviv airport, Mr Obama said US commitment to the security of Israel was rock solid.
"I see this visit as an opportunity to reaffirm the unbreakable bond between our nations, to restate America's unwavering commitment to Israel's security and to speak directly to the people of Israel and to your neighbours.
"I am confident in declaring that our alliance is eternal, is forever."
Israeli President Shimon Peres and Prime Minister Benjamin Netanyahu welcomed Mr Obama to Israel.
Mr Netanyahu said: "Thank you for standing by Israel at this time of historic change in the Middle East.
"Thank you for unequivocally affirming Israel's sovereign right to defend itself by itself against any threat."
The war in Syria and concerns over Iran's nuclear ambitions are expected to top the agenda in talks with both men.
Mr Obama will also hold separate talks with Palestinian President Mahmoud Abbas in the West Bank during his three-day visit to the Middle East, which also includes a visit to Jordan.
US officials have said he will try to coax the Palestinians and Israelis back to peace talks.
He will also seek to reassure Mr Netanyahu he is committed to preventing Iran from getting a nuclear bomb and to discuss ways of containing Syria's civil war.
Israel and the US agree that Iran should never get a nuclear bomb, dismissing Iran's assertion that its nuclear programme is peaceful.
The White House has deliberately minimised hopes of any major breakthroughs, a reversal from Mr Obama's first four years in office, when aides said he would only visit Israel if he had something concrete to accomplish.
Mr Obama will tomorrow travel the short distance between Jerusalem and the West Bank city of Ramallah to meet Mr Abbas.
He is accompanied by his Secretary of State John Kerry.
A few hours before Mr Obama landed in Israel, Mr Netanyahu received an invitation from Russian President Vladimir Putin to visit Moscow, an Israeli official said.
However, he did not specify a date for the visit. That trip would follow a visit to Moscow last week by Mr Abbas.
Palestinians protest at new Jewish settlement
Meanwhile, Palestinian activists have set up a protest camp close to where Israel wants to build a new settlement in the occupied West Bank, drawing attention to their struggle during Mr Obama's visit to the region.
Over 100 demonstrators erected four large, steel-framed tents and a massive Palestinian flag on the rocky tract near Jerusalem, just as Mr Obama arrived in nearby Tel Aviv.
"We are here to send a message to President Obama, our struggle, our non-violent peaceful resistance will continue until we are free," said senior Palestinian politician Mustafa Barghouthi.
Israeli police entered the tent colony and told protesters to clear the area, which they called a "closed military zone," but did not immediately try to tear down the camp.
Palestinians complain that Mr Obama has not put enough pressure on Israel to halt the settlements and warn that the prospect of creating a viable, independent state is fading fast.
Mr Netanyahu announced in December plans to build hundreds of settler homes in a sensitive area on Jerusalem's outskirts that is known by its administrative name E1.