By Matt Spetalnick
WASHINGTON, April 23 (Reuters) - Seeking to ease U.S.-Israeli tensions, Vice President Joe Biden on Thursday promised Israel delivery of top-flight fighter jets next year to maintain its military edge and vowed that any final nuclear deal with Iran would ensure Israel's security.
Addressing an Israeli Independence Day celebration in Washington, Biden insisted that Barack Obama "has Israel's back," despite a recent strains between the U.S. president and Prime Minister Benjamin Netanyahu over Iran nuclear talks and Middle East diplomacy.
Biden won applause from a pro-Israel audience when he told them the United States would begin delivery of Lockheed Martin's new F-35 jets to its ally next year, making Israel the only country in the Middle East to have the new stealth warplane.
But he was met with silence when he reaffirmed U.S. support for a two-state solution to the Israeli-Palestinian conflict, an allusion to White House objections to Netanyahu's comments last month casting doubt on his commitment to a Palestinian state.
"We've had our differences," Biden said. But he added: "We love each other and we protect each other."
Biden's appearance at an event hosted by the Israeli Embassy was the latest sign of White House efforts to lower the temperature after a period of acrimony between Obama and Netanyahu.
Ties became badly frayed early last month when Netanyahu accepted a Republican invitation to speak to the U.S. Congress, where he railed against Obama's quest for a nuclear deal with Iran. Netanyahu later condemned a framework deal reached earlier this month with Tehran as a threat to Israel's survival.
Obama, who has faced complaints from some fellow Democrats that the public feud had gone too far, has reached out to U.S. pro-Israel groups and American Jewish leaders seeking to soothe their concerns.
Biden sought to reassure his audience of Obama's commitment to making sure that any final nuclear agreement with Iran maintains Israel's security.
But with talks now aimed at reaching a comprehensive accord with Tehran by a June 30 deadline, there is little chance of a meeting of the minds between Obama and Netanyahu, who have a long history of testy relations.
Biden said any deal with Iran would be "based on hard-hitting, hard-headed uncompromising assessments, what's required to protect ourselves, Israel, the region and the world."
If a final deal does not meet Obama's requirements, Biden said, "we simply will not sign it."
And he warned: "If Iran cheats at any time and goes for a nuclear weapon, every option we have to respond today remains on the table and - your military will tell you - and more."
Iran denies seeking a nuclear bomb. Israel is widely assumed to be the Middle East's only nuclear-armed state.
Biden was hosted by Israeli Ambassador Ron Dermer, a Netanyahu confidante blamed by Obama's aides for orchestrating the prime minister's congressional address.
Dermer acknowledged disagreements but said the two allies would weather them. Biden's speech marked the administration's highest-level direct contact with the Israeli government since Netanyahu's speech to Congress.
Touting U.S. efforts to maintain Israel's "qualitative advantage" in the Middle East, Biden said: "Next year we will deliver to Israel the F-35 Joint Strike Fighter, our finest."
Israel bought 19 F-35s in 2010 for $2.75 billion and signed a contract in February to buy an additional 14 of the Lockheed Martin Corp fighter jets for about $3 billion. (Reporting by Matt Spetalnick; Editing by Peter Cooney and Eric Beech)