Obama has declared the use, deployment or transfer of the weapons would be a "red line" for possible military intervention by the U.S. in the Syrian conflict. Ahead of Obama's visit, authorities in Israel said they believed that chemical weapons may have been recently used in Syria, although U.S. officials have said they had no evidence to support the Syrian regime's claims that rebels were responsible for a chemical attack.
Even though U.S. officials have set expectations low and previewed no major policy pronouncements, a clear measure of the success of Obama's Israel trip will be how much he is able to reverse negative perceptions.
The centerpiece of the visit will be a speech to Israeli university students on Thursday, during which Obama will again renew U.S. security pledges to Israel as it seeks to counter threats from Iran, protect its people from any spillover in the Syrian civil war and maintain its shaky peace accord with an Egypt that is now controlled by the Muslim Brotherhood.
Obama will make an almost perfunctory visit to the cash-strapped Palestinian Authority's headquarters in the West Bank town of Ramallah, where he will meet the embattled Abbas and assure him that an independent Palestinian state remains a U.S. foreign policy and national security priority.
As Israelis warmly greeted Obama, Palestinians held several small protests in the West Bank and Gaza. Demonstrators in the Hamas-ruled Gaza Strip burned posters of Obama and U.S. flags, accusing the U.S. of being biased toward Israel.
In the West Bank, about 200 activists erected about a dozen tents in an area just outside of Jerusalem to draw attention to Israel's policy of building settlements. The tents were pitched in E1, a strategically located area where Israel has said it plans on building thousands of homes. The U.S. has harshly criticized the plan.
Israeli forces have swiftly dismantled similar encampments built by Palestinians in the past. Abdullah Abu Rahmeh, one of the activists, said Israeli forces surrounded the tent camp but had not moved in.
Despite not coming with any new plan to get the stalled peace process back on track, Obama plans to make clear that his administration intends to keep trying to get talks re-launched.
Obama will close out his Mideast trip with a 24-hour stop in Jordan, an important U.S. ally, where his focus will be on the violence in Syria. More than 450,000 Syrians have fled to Jordan, crowding refugee camps and overwhelming aid organizations.
In his talks with Jordan's King Abdullah, Obama also will try to shore up the country's fledgling attempts to liberalize its government and stave off an Arab Spring-style movement similar to the ones that have taken down leaders elsewhere in the region.
Associated Press writers Mohammed Daraghmeh in Ramallah, West Bank, and Ibrahim Barzak in Gaza City, Gaza Strip, contributed to this report.