When Chairman of the US Joint Chiefs of Staff Admiral Michael Mullen examines the honor guard that will greet him at the Kirya Military Headquarters on Monday he will be met not just by young stern-faced IDF soldiers, but also by an entire defense establishment eager to try and change his country's assessment of the Iranian nuclear threat. Mullen's visit to Israel is not his first. He was here last May together with his wife. Then, however, he was commander of the US Navy. His arrival in Israel on Sunday is the first time a top American military commander has visited Israel in the past decade. It is not clear that Mullen's visit to Israel was timed to coincide with last week's publication of the US National Intelligence Estimate that claimed Iran had frozen its program to develop a nuclear weapon back in 2003 and has yet to restart it. Either way, his visit as well as President George Bush's planned trip to Jerusalem next month, are clear attempts by the US to show Israel that it is not alone in the face of what Prime Minister Ehud Olmert has called the "greatest existential threat" in this country's short 60-year history. US Secretary of Defense Robert Gates hinted to this effort on Saturday when he spoke at the Manama Dialogue conference and defended - to the laughter of the audience - Israel's alleged nuclear program. At the Kirya, Mullen will sit through a number of lengthy briefings by intelligence and military officials on a wide range of topics, including Israel's views on Iran's continued race toward nuclear power. The defense establishment is not kidding itself and does not bank on Mullen suddenly having a change of heart. As reported in Time magazine last week, Mullen is a member of the anti-war-with-Iran group in the Pentagon that also includes Gates and Admiral William Fallon, current commander of the US Central Command. "It is unlikely that Israel will succeed in changing the report," said former head of the National Security Council Maj.-Gen. (ret.) Giora Eiland. "The report is based on assessments - theirs against ours - and since we don't have a smoking gun to prove otherwise, it will stay the same for now." That doesn't mean Israel won't try to find the smoking gun. As Olmert told the security cabinet Sunday, Israel will work with the International Atomic Energy Agency to expose Iran's military nuclear program. "Israel has no reason to change the assessments it has had all along that Iran is continuing to pursue nuclear weapons and is developing weapons and rockets and enriching uranium," Olmert said. The thinking within the defense establishment is that, despite the report, there is still a chance to impose additional sanctions on Iran and in that way slow down the country's nuclear progress, if not stop it altogether. At the same time, however, Israel is aware that, as in the past, it might be left alone to deal with Iran militarily. If it comes to that and the Americans sit on the sidelines, their assistance will still be needed. Without the codes to American fighter jets in the region - particularly those operating over Iraq and Afghanistan - an Israeli aerial operation would go from extremely difficult to almost impossible. When Israel requested these codes in 1991 during the First Gulf War to respond to Saddam Hussein's Scud attacks, the US said no and the Israeli planes stayed at their bases. So while the IDF might not succeed in convincing Mullen of Iran's intentions, it should be investing no fewer efforts in ensuring that, when the time comes, its Number One ally will deliver.