President Nixon's top national security adviser worried that Israel might produce nuclear warheads "clandestinely" and that Israel's ambassador to the United States at the time, Yitzhak Rabin — later Israel's prime minister — might "stonewall" the White House in its efforts to ascertain the Israel's true intentions, according to newly declassified documents.

The papers also show the Nixon administration possessed "circumstantial evidence" that Israel built its nuclear arsenal with "some fissionable material...illegally obtained from the United States" at an unspecified time prior to 1965.

The disclosures emerged in some 123,000 pages of Nixon-era documents released by the National Archives on Wednesday, pages that underscored the ambivalence and alarm toward the prospect of a nuclear-armed Israel that prevailed in both the Johnson and Nixon White Houses.

Israel has long maintained a studied vagueness about whether it possesses nuclear weapons, however current Israeli Prime Minister Ehud Olmert appeared to remove any doubts about the matter when, during a German television interview last December, he claimed Iran is "aspiring to have nuclear weapons, as America, France, Israel, Russia."

Although Israel is believed to have possessed a formidable nuclear arsenal since the mid-1970s, Olmert's aides claimed he had merely "listed Israel among the list of responsible nations, and not the list of nations which have nuclear weapons."

The newly declassified documents show the U.S. in the late 1960s and early 1970s worried about the potential for a Mideast arms race — and a nuclear confrontation with the Soviet Union — if Israel acquired a nuclear weapons capability, and that senior American official consistently sought, through diplomatic and defense channels, to dissuade the Israelis from doing so. At the same time, officials here viewed the prospect as largely inevitable, and schemed to ensure the historical record would show that the U.S. "had no complicity" in the enterprise.

This scheme, too, however, was thought to be a lost cause. "Regardless of what we say," Nixon was told, "the Arabs will assume that we could have stopped Israel."

National security adviser Henry A. Kissinger told Nixon, in a lengthy memorandum dated July 19, 1969 and classified "Top Secret," that the Israelis "will not take us seriously on the nuclear issue" unless Washington made clear to then-Prime Minister Golda Meir and the members of her cabinet that the U.S. was "prepared to withhold something they very much need."

The best leverage the White House had, Kissinger argued, was to withhold delivery of Phantom fighter jets which Israel had contracted to purchase from the U.S. in 1968, and which could be used to deliver a nuclear warhead; or to threaten "their whole military supply relationship with us."

However, Kissinger, a Jew who fled Hitler's Germany before coming to the United States, also recognized Nixon would be subjected to "enormous political pressure" from domestic Jewish groups if he followed either of those courses. At a minimum, Kissinger reckoned, Israel was "concerned enough about its relations with us...to think twice about putting nuclear weapons openly in its arsenal."

According to the memorandum, the Joint Chiefs of Staff, then chaired by Army General Earle G. Wheeler, felt the U.S. "should be in a position to say we did everything in our power to prevent Israel from going nuclear ... should try to stop Israel's missile production and use the Phantoms as leverage."

Defense Secretary Melvin Laird, a former Wisconsin congressman, disagreed, telling Nixon the U.S. "could live with" Israeli nuclear weapons "provided they were not deployed." The State Department, led by then-Secretary of State William Rogers, sided with the Joint Chiefs, arguing the U.S. "should try to keep Israel from going any further with its nuclear program."

Despite these differences, an inter-agency task force that included these offices and players agreed unanimously that the Israelis, as "one of the few peoples whose survival is genuinely threatened, are probably more likely than almost any other country to actually use their nuclear weapons."

Known for his masterful manipulation of language and his heavy use of private "back-channels" of negotiation, Kissinger weighed in with a characteristically slippery proposal, recommending to Nixon that the administration should "for our own internal purposes ... decide that we could tolerate Israeli activity short of assembly of a completed nuclear device," and should in the meantime "find an excuse," unrelated to the nuclear issue, for not immediately delivering the Phantom jets.

Rabin ultimately took his complaints about the withholding of the Phantoms to then-Attorney General John Mitchell, who privately persuaded Nixon to deliver them to the Israelis.

The White House had also feared how the Soviet Union would react to the introduction of nuclear weapons into the Middle East, where Moscow enjoyed strong relationships with many of Israel's hostile Arab neighbors.

"We do not know exactly how much the Soviets know about Israel's nuclear development," Nixon was told. "However, the director of Central Intelligence [Richard M. Helms] believes that, while Moscow may not have quite as much detail as we do, the Soviets must be aware of the general state of Israel's nuclear weapons and missile development, though they may not want it publicly known."

The Americans believed the Kremlin might balk at bankrolling a concerted Arab effort to match the Israeli nuclear capability, which was sure to arise if the Israeli program became known, and that the Soviets might therefore "have an incentive not to know."

Public disclosure of the research underway at the Israeli nuclear facility at Dimona, a Negev desert town south of Beersheba, was thus considered "almost as dangerous as possession itself." On this basis, Kissinger told Nixon that while it would be "ideal" for the Americans to persuade the Israelis to desist in their quest for the atom, "what we really want at a minimum may be just to keep Israeli possession [of a nuclear weapons capability] from becoming an established international fact."

The documents also reveal that American nuclear experts toured the facility at Dimona in early July 1969. A memorandum Kissinger sent to Nixon, dated August 7, 1969 and marked "Top Secret," disclosed that the team "felt the Israelis did not allow enough time for an adequate examination" and that Meir had, only days before Kissinger sent the memo, turned down the White House's request for a one-day return visit to Dimona.

The American ambassador to Israel "pressed the Israelis as hard as he can on inspection," Kissinger reported, but added there was "no hope" the prime minister would yield anytime soon.

The multiple Catch-22 contortions into which the Israeli nuclear program forced the Nixon White House — wanting to dissuade the Israelis from pursuing the program without creating any record showing the U.S. knew about it, while simultaneously debating options and thereby creating just such a record — led the inter-agency task force advising Nixon to a classic moment of bureaucratic absurdity.

In recommending for further study the option that the U.S. seek to convince Israel not to publicize its "assembly of completed nuclear explosive devices," the task force's report to Kissinger stated: "This is what we really want to stop since it may be the only thing, if anything, that we can stop. For purposes of the record, however, we may not want to state our objective this way, not even to ourselves."

Despite the many tumultuous changes in the Middle East since the Nixon era — including the rise of fundamentalist Islamic movements and their expanded use of terrorism, in and out of the region — the declassified documents also showed how some things remain unchanged. A "secret" letter to Kissinger from Helms, dated July 18, 1970 and still heavily redacted, noted that Israel believed "her future security depended on some kind of balance of power between the revolutionary and the moderate Arabs."

James Rosen joined Fox News Channel (FNC) in 1999. He currently serves as the chief Washington correspondent and hosts the online show "The Foxhole." His latest book is "Cheney One on One: A Candid Conversation with America's Most Controversial Statesman" (Regnery, November 2, 2015).