The Obama administration Thursday warned Iran and Syria that America's commitment to Israel's security is unshakable and that they should understand the consequences of threats to the Jewish state.Previewing a speech Secretary of State Hillary Rodham Clinton is to deliver later Thursday, the State Department said transfers of increasingly sophisticated weaponry, including rockets, to anti-Israel militants in southern Lebanon and Gaza could spark new conflict in the Middle East."These are issues that are fundamental to war and peace in the region," spokesman P.J. Crowley told reporters ahead of the Clinton's address to the American Jewish Committee. The speech is the latest in a series of moves the administration is making to reassure Israel that its ties to the United States remain strong despite tensions that flared last month.Clinton will speak to the "very real threats" that Israel faces, particularly from Iran, Syria and groups they support like Hizbullah in Lebanon and Hamas in the Gaza Strip and reaffirm US determination to get them to change course, he said.Israel has accused Syria of providing Hizbullah with Scud missiles, weapons that would dramatically increase the group's range to hit targets in Israel. Syria has denied the charges. US officials have not confirmed Hizbullah's possession of Scuds, but say they are concerned about its growing arsenal of rockets and missiles."We are concerned about the broader issue of the nature of Syrian support to Hizbullah involving a range of missiles, including that one," Crowley said. He added that US intelligence was looking at "multiple systems" from "multiple sources," including Syria, that Hizbullah may have.Getting Syria to stop, he said, is one of the administration's prime goals in returning an ambassador to Damascus. The US has been without an ambassador in Syria for five years and the nominee for the position, career diplomat Robert Ford, is still awaiting Senate confirmation. Some lawmakers have questioned the wisdom of sending an envoy to Syria now, saying it would reward the country for bad behavior. Clinton will argue that it would not be "a reward or concession," but rather "a tool that can give us added leverage and insight and greater ability to convey strong and clear messages aimed at changing Syria's behavior."On Iran, Clinton will say the administration is still open to engaging with Tehran but that it must meet international demands to prove its suspect nuclear program is peaceful as it claims and not a cover for developing atomic weapons. Short of that, the US will continue to press for tough new UN Security Council sanctions on Iran.Iran has been on a diplomatic mission to forestall fresh sanctions and Iranian President Mahmoud Ahmadinejad may try to use a nuclear conference at the United Nations next week to lobby against them.Before her speech, Clinton said any attempt by Ahmadinejad to undermine the purpose of the conference — to review, revise and improve the nuclear Non-Proliferation Treaty — would fail."If he believes that by coming he can somehow divert attention from this very important global effort or cause confusion that might possibly throw into doubt what Iran has been up to, ... then I don't believe he will have a particularly receptive audience," she told a news conference with visiting Polish Foreign Minister Radek Sikorsky.In her speech, Clinton will also say the US will continue to pursue an Israeli-Palestinian peace deal and is hoping to restart indirect talks between the two sides in the near future, according to Crowley."We are working around the clock to move forward with proximity talks, which we hope will set the stage for a resumption of direct negotiations on all permanent status issues as soon as possible," he said.The administration's special Mideast envoy George Mitchell is due back in the region next week. His visit will follow a weekend meeting of Arab League diplomats at which US officials hope for an endorsement of the indirect talks that Mitchell will mediate. An attempt to get those talks started last month fizzled when Israel announced a new Jewish housing project in east Jerusalem, which the Palestinians claim as a future capital. That drew fierce criticism from the United States and led to the worst rift between Washington and its top Mideast ally in decades.Since then, the administration has sought to repair the damage with a series of recent meetings and speeches from senior officials, including Clinton and national security adviser James Jones.