washington | President Truman threatened to break with Israel unless it allowed the return of some Palestinian refugees displaced in Israel’s 1948 War of Independence, documents newly unearthed by the U.S. Holocaust Memorial Museum show.

The diaries of James McDonald, a top League of Nations refugee official from 1933 to 1935 and the first U.S. ambassador to Israel, have provided a trove of insights into that period, which echo today in the ongoing controversy over the status of Palestinian refugees.

McDonald’s records of his interaction with Egenio Cardinal Pacelli — the Vatican secretary of state who later became Pope Pius XII — also bear on current Vatican-Jewish relations, which have been strained by accusations that Pacelli didn’t do enough to save European Jews threatened with extermination.

McDonald, who expresses unvarnished affection for many of the Jewish and Zionist leaders of the day in his 12,000 pages of diaries, learned of Truman’s threat on June 9, 1949, from Abe Feinberg, a U.S. Jewish leader who acted as an interlocutor between the U.S. and Israeli governments.

McDonald described the threat as “startling.” Israel “would have to choose between a break with him and making a constructive contribution to the refugee solution,” he writes.

In response, he says, Israel’s leaders considered allowing 100,000 refugees to return.

It was known that David Ben-Gurion, Israel’s first prime minister, had tentatively made such an offer toward a non-aggression pact with Arab states that had attacked Israel, but the degree of Truman’s personal involvement in pressuring Israel is news, according to Severin Hochberg, a senior historian at the museum.

“It’s known to some extent that Truman had problems with the Israelis from 1948 to 1950,” Hochberg said. “But it was much more tense than is the common view.”

The same refugee issues that Truman and Ben-Gurion dealt with were in the news again last week, when President Bush became the first U.S. president to formally reject the Palestinians’ claimed right of return to Israel.

The 100,000 number was resurrected during the Camp David talks of 2000 and was cited by negotiators in last year’s non-binding “Geneva accord” between freelance Israeli and Palestinian negotiators.

McDonald chronicles other Truman-Ben-Gurion tensions in his diaries, adding nuance to Truman’s reputation as sentimentally pro-Israel.

Responding to an Israeli thrust in the Negev toward Egyptian forces in late December 1948, McDonald describes Truman using language like “grave consequences” and “review of our attitudes towards Israel.” Truman was concerned that Israeli incursions into Egyptian territory would draw Britain into the fight.

Another revelation is the degree to which McDonald had to reassure his bosses that Israel would not drift into the Communist camp. After a November 1948 meeting with U.S. Secretary of State George Marshall — who was never sympathetic to the Jewish state — McDonald speaks of having to persuade Marshall “of my conviction that the Communist bogie was without substance.”

“The people as well as their leaders knew that the USSR embrace was that of death, that the tiny Communist party could not hope to grow unless the West left the USSR as Israel’s friend,” he writes.

In latter passages, it’s clear McDonald had a hand in Ben-Gurion’s decision to come down firmly on the side of the United States on the Korea issue, a diplomatic stand that placed Israel once and for all in the Western camp.

In page after page of his diaries, McDonald evinces real sympathy for the Jewish and Zionist leaders he encounters. As a member of the 1946 Anglo-American Committee of Inquiry on Palestine, he describes Ben-Gurion’s testimony as “leaving no doubt that there would be, if necessary, resistance to any move to liquidate or seriously weaken the Jewish position in the country.”

McDonald, who died in 1964, famously quit the League of Nations with a speech accusing the body of ignoring the plight of Germany’s Jews.

The Holocaust museum stumbled onto the diaries in 2003 when the daughter of a man who once considered writing a biography of McDonald offered the museum about 500 pages — covering his League of Nation years — that she had uncovered among her belongings.

That led the museum to track down McDonald’s two daughters, who agreed to donate the other 11,500 pages. The museum was slated to dedicate the diaries formally on Thursday, April 22.