When the George W. Bush administration unveiled a $20 billion arms package spread over 10 years for its Arab allies -- led by Saudi Arabia, Egypt and Jordan -- in 2007, it emphasized the weapons were needed to confront an expansionist Iran.
A U.S. pledge that it would maintain Israel's technological edge over its Arab neighbors, and a larger $30 billion arms package for the Jewish state that included new strike jets and bunker-busting bombs, muted the usual Israeli objections to giving the Arabs advanced weaponry.
What all this meant was that the Americans were arming both sides of the traditional Arab-Israeli arms race to contain Iran.
According to the International Institute for Strategic Studies in London at the time, the U.S. action was possibly aimed at securing Arab acquiescence for future U.S. -- or Israeli -- airstrikes against Iran's nuclear infrastructure if Tehran continued to enrich uranium.
Given that the six Arab states of the Gulf Cooperation Council, dominated by Saudi Arabia, are almost as afraid of what Iran will do if it is attacked as they are of a nuclear-armed Islamic Republic on their doorstep, that prospect seems less likely now than it might have in late 2007.
But Israeli concerns about the scale and content of U.S. arms deals with the Arabs seem to have been invigorated when the Pentagon notified Congress of major deals it wished to conclude with the Gulf states, Egypt and Jordan.
The Department of Defense stressed in the notification that none of the contracts would "alter the military balance in the region."
Just what has sharpened Israeli unease at the prospect of Arab states -- even if they are classified as "moderate" by the Americans -- getting such a weight of state-of-the-art firepower at this time is not altogether clear.
But according to The Forward, a U.S. Jewish weekly, Israeli defense chiefs have been complaining to the Barack Obama administration that the "usage and deployment" of the arms in the $20 billion package for the Arabs "breached earlier understandings and could tilt the military balance against Israel."
The Forward says the U.S. response to the Israeli arm-twisting has been highly favorable and may have been an effort to address serious misgivings among Israelis about Obama's intentions in the Middle East.
These focus particularly on the White House's emphasis on negotiations with Tehran rather than military action, as many Israelis advocate, and its demands of an open-ended freeze on Jewish settlement expansion in the West Bank to kick start the long-stalled peace process.
The Forward quoted one analyst as concluding that the Obama administration was open to supplying Israel with advanced technology to maintain its edge, to ensure Israeli confidence in the United States, and possibly to convince it not to undertake unilateral military action against Iran.
Another factor in the shift in Israeli concerns about what weaponry the Arabs get may lie in the outcome of a war game conducted by Tel Aviv University's Institute for National Security Studies, one of Israel's top think tanks, in early November.
The conclusion was that Israel would find itself diplomatically sidelined and militarily constrained as Washington pursued a nuclear deal with Iran in 2010.
According to the liberal Israeli daily Haaretz, one of the proposed U.S. deals troubling the Israelis concerns providing Egypt with 20 RGM-84L Harpoon Block II anti-ship cruise missiles worth $145 million.
In the past, the Israelis persuaded Washington to exclude software that allows Egyptian Harpoons to hit land-based targets because the tiny Jewish state would be vulnerable to such capabilities.
It is not clear whether the missiles the Pentagon wants to sell to Cairo would have that capability restored.
Israel is also concerned about a $290 million deal with the United Arab Emirates for advanced weaponry for its Lockheed Martin F-16s, including 1,600 laser-guided "smart" bombs and 400 bunker-busters.
"Even though the United Arab Emirates does not pose a threat to Israel and is not considered an enemy state, officials in Jerusalem are concerned about this deal as well," Haaretz reported.