SDEROT, ISRAEL - Tough talk on Iran dominated Barack Obama's meetings Wednesday in Israel and the West Bank, as Israeli officials amplified their enemy's threat and the Democratic presidential hopeful declared that a "nuclear Iran would be a game-changing situation."

Speaking at an afternoon news conference in Sderot, a city near the Gaza Strip that has long been a target for Palestinian rocket attacks, Obama said that "the world must prevent Iran from obtaining nuclear weapons" and that "America must always stand up for Israel's right to defend itself against those who threaten its people."

The Illinois senator warned that no options are "off the table" in confronting a nuclear threat from Iran, though he added that Iran should be offered "big carrots" as well as "big sticks."

Obama's aggressive rhetoric on Iran followed his emphasis earlier this week on his plan to send more U.S. troops to fight terrorism in Afghanistan should he defeat Republican John McCain in November. Obama has also made clear that he remains committed to withdrawing combat troops from Iraq over 16 months and that he still sees merit in talking to enemy nations, including Iran. But his rhetoric has taken on a more militaristic tone than was typical in his primary election campaign.

Iran was a recurring theme throughout Obama's private meetings Wednesday with Israel's President Shimon Peres, Labor leader and Defense Minister Ehud Barak, Likud leader Benjamin Netanyahu, Foreign Minister Tzipi Livni and Prime Minister Ehud Olmert.

Olmert told Obama in remarks to reporters that "the situation in Iran is of course a main concern for the people of Israel," as are tensions involving the Palestinians and Syrians.

Livni said the problem in the Middle East is between moderates and extremists rather than Israelis and Arabs, and that some of the rockets fired into Sderot are Iranian-made. "Terror is terror is terror," she said.

Netanyahu told reporters after his earlier meeting with Obama that "the senator and I agreed that the primacy of preventing Iran from becoming a nuclear power is clear and this should guide our mutual policies." Netanyahu said that "achieving this goal is more important than how you achieve it, but it's terribly important to achieve it."

Iran seemed to eclipse the tensions between Israel and the Palestinians as a concern, although the latter remained on everyone's agenda.

Obama also traveled to Ramallah in the West Bank for an hourlong visit with President Mahmoud Abbas and Prime Minister Salam Fayad. At his news conference in Sderot, Obama said Israel and the United States need to support moderate Palestinian leaders such as those two, who accept the legitimacy of Israel and renounce violence.