White House hopeful Barack Obama vowed to tighten US bonds with Israel as he began an intense day of talks with Israeli and Palestinian leaders.

The Democratic contender was also to tour the Yad Vashem Holocaust memorial and to take a helicopter tour of Israel's cramped topography, a rite of passage for potential US leaders.

Obama, who flew in from Jordan and Iraq late Tuesday, opened his day with a meeting at his Jerusalem hotel with Israeli Defence Minister Ehud Barak, the first engagement on a presidential-style schedule.

He was later due to see Prime Minister Ehud Olmert and Foreign Minister Tzipi Livni, and to travel to Ramallah in the West Bank to consult Palestinian president Mahmud Abbas.

Later Wednesday, Obama was also due in Sderot, a southern Israeli town that has long been in the firing line of rockets and mortars from the Hamas-controlled Gaza Strip.

After touching down at Tel Aviv airport following a short flight from Jordan, Obama made a brief statement, saying it was "wonderful to be back in Israel."

"I want input and insight from Israeli leaders about how they see the current situation. I will share some of my ideas," Obama said.

"The most important thing for me to share is the historic and special relationship between the United States and Israel, one that cannot be broken.

"One that I have affirmed throughout my career and one that I will intend to not only continue but strengthen in an Obama administration."

Hours before his arrival, regional tensions intruded when a Palestinian man was shot dead after launching a bulldozer rampage that wounded at least 16 people near the King David Hotel where Obama is staying.

Obama condemned the attack, saying it was "a reminder of what Israelis have had to courageously live with on a daily basis for far too long," and promised to vigorously join the search for Middle East peace if he is elected in November.

Israeli police said they had tightened security immediately after the bulldozer attack - the second such incident in three weeks - and that the state of alert would remain until after Obama's visit.

The Illinois senator, who is being advised by ex-president Bill Clinton's former Middle East envoy Dennis Ross, backed a two-state solution to the Israeli-Palestinian conflict.

Obama's audience for this visit is not just in the Middle East, but back home where he has struggled to win the overwhelming support among Jewish voters enjoyed by some previous Democratic candidates.

Earlier, a day before meeting Israeli and Palestinian leaders, he warned that entrenched positions, divisions among Palestinians and turbulent Israeli politics meant progress could be slow.

"It is a very difficult process. There is a lot of history that exists between those two people. That history is not going to vanish overnight.

"So I think it's unrealistic to expect that a US president alone can suddenly snap his fingers and bring about peace in this region."

While Obama is likely to be greeted as a hero in Europe, there remain questions in the Middle East about his potential policies.

His view that Jerusalem must remain the undivided capital of Israel sparked fury among Palestinians, who saw it as pre-judging final status talks on their promised future state, while his offer to talk to Iran is likely to face scrutiny in Israel.

A Jordanian palace statement said that in his talks with Obama on Tuesday, King Abdullah II stressed that ending the Israeli occupation of Palestinian land and achieving a just settlement to the Arab-Israeli conflict "tops the priorities of the people of the Middle East."

"The king told Obama that continued American support for a Middle East peace process that leads to a just and comprehensive peace would help foster Arab-US relations and bolster US credibility in the region," the statement added.

From Israel, Obama will head to Germany for the symbolic centrepiece of his campaign swing, a major open-air speech in Berlin on US transatlantic relations.