WASHINGTON, Nov. 28 — In July 1969, as the world was spellbound by the Apollo 11 mission to the moon, President Richard M. Nixon and his close advisers were quietly fretting about a nuclear arms race in the Middle East. Their main worry was not a potential enemy of the United States, but one of America’s closest friends.

Tensions over Israel’s nuclear weapons cast a shadow over talks between Richard M. Nixon and Golda Meir in 1969.

Related

Mandatory Review Documents (nixon.archives.gov)

Memo From Kissinger to Nixon on the Israeli Nuclear Program (July 19, 1969)

“The Israelis, who are 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,” Henry A. Kissinger, the national security adviser, warned Mr. Nixon in a memorandum dated July 19, 1969 — part of a newly released trove of documents.

Israel’s nuclear arms program, which Israel has never officially conceded exists, was believed to have begun at least several years before, but it was causing special problems for the young Nixon administration. For one thing, the president was preparing for a visit by its prime minister, Golda Meir, who was also in her first year in office and whose toughness was already legendary.

Should Washington insist that Israel rein in its development of nuclear weapons? What would the United States do if Israel refused? Perhaps the solution lay in deliberate ambiguity, or simply pretending that America did not know what Israel was up to. These were some of the options that Mr. Kissinger laid out for Mr. Nixon on that day before men first walked on the moon.

The Nixon White House’s concerns over Israel’s weapons were detailed in documents from the Nixon Presidential Library that were released on Wednesday by the National Archives under an executive order that requires that classified documents be reviewed and possibly declassified after 25 years.

The documents provide insights into America’s close, but by no means problem-free, relationship with Israel. They also serve as a reminder that concerns over nuclear arms proliferation in the Middle East, now focused on Iran, are decades old.

The papers also allude to a 1972 campaign by friends of W. Mark Felt, then the second-ranking F.B.I. official, to have him named director of the bureau after the death of J. Edgar Hoover in May of that year. Mr. Nixon, of course, did not take the advice, instead naming L. Patrick Gray. Mr. Felt later became the famous anonymous source “Deep Throat,” whose revelations during Watergate helped topple the president.

There are also snippets about Washington’s desire to manipulate relations with Saudi Arabia, so that the Saudis might help to broker a Middle East peace deal; discussion of possibly supporting a Kurdish uprising in Iraq; and a 1970 clash in which four Israeli fighters shot down four Russian MIG-21s over eastern Egypt, even though the Israelis were outnumbered by two-to-one.

But perhaps the most interesting material, and the most pertinent given the just-completed peace conference in Annapolis, Md., concerns Israel and its relations with its neighbors, as well as with the United States.

“There is circumstantial evidence that some fissionable material available for Israel’s weapons development was illegally obtained from the United States about 1965,” Mr. Kissinger noted in his long memorandum.

He also said that one problem with trying to persuade Israel to freeze its nuclear program was that inspections would be useless, conceding that “we could never cover all conceivable Israeli hiding places.”

“This is one program on which the Israelis have persistently deceived us,” Mr. Kissinger said, “and may even have stolen from us.”

Although Israel has never publicly acknowledged possessing nuclear weapons, scientists and arms experts have no doubt that it has them, and the United States’ reluctance to pressure Israel to disarm has made America vulnerable to accusations that it has a double standard when it comes to stopping the spread of weapons in the Middle East.

Mr. Kissinger’s memo, written barely two years after the 1967 Middle East war and while memories of the Holocaust were still vivid among the first Israelis, implicitly acknowledged Israel’s right to defend itself, as subsequent American administrations have done.

But Mr. Kissinger reflected at length on the quandary faced by the United States. “Israel will not take us seriously on the nuclear issue unless they believe we are prepared to withhold something they very much need,” he wrote, referring to a pending sale of Phantom fighter jets to Israel.

“On the other hand, if we withhold the Phantoms and they make this fact public in the United States, enormous political pressure will be mounted on us,” Mr. Kissinger went on. “We will be in an indefensible position if we cannot state why we are withholding the planes. Yet if we explain our position publicly, we will be the ones to make Israel’s possession of nuclear weapons public with all the international consequences this entails.”

One of those consequences might be to “spark a Soviet nuclear guarantee for the Arabs, tighten the Soviet hold on the Arabs and increase the danger of our involvement,” Mr. Kissinger wrote at another point.

After he met with Mrs. Meir at the White House in late September 1969, Mr. Nixon said: “The problems in the Mideast go back centuries. They are not susceptible to easy solution. We do not expect them to be susceptible to instant diplomacy.”

But Avner Cohen, the author of “Israel and the Bomb,” (Columbia University Press, 1998) who is a senior fellow at the United States Institute of Peace, said on Wednesday that there was enough historical evidence to indicate that the president and the prime minister had reached a secret understanding on at least one issue: Israel would keep its nuclear devices out of sight and not test them, and the United States would tolerate the situation and not press Israel to sign the Nuclear Nonproliferation Treaty that has been embraced by scores of countries around the world.

“That understanding remains to this day,” Mr. Cohen said.