The First Lady listened impassively as Suha Arafat accused the Israeli government of deliberately poisoning Palestinian women and children. When it was time to leave, Hillary Clinton embraced and kissed the PLO leader's wife.

It was only the next day, as her husband's horrified White House realised what had occurred, that Mrs Clinton's condemnation of Mrs Arafat's incendiary claims was issued.

This was not simply a misstep by a First Lady on a goodwill tour designed to bolster the flagging peace process. By November 1999, Mrs Clinton was a candidate for the Senate in New York, the most heavily Jewish state in America. Months later - despite repeatedly explaining that a kiss was akin to a handshake in the Middle East and that there had been something awry in the translation of Arafat's remarks she had been listening to - the issue continued to dog her on the campaign trail.

While it was not the first time that Mrs Clinton had found herself in the hot waters of Middle Eastern politics - a year earlier, in contradiction to US policy at the time, she had publicly backed the creation of a Palestinian state - it was the episode in Ramallah, one of Mrs Clinton's aides recently revealed, which had "haunted" her ever since.

Since that time, the habitually cautious Democrat presidential candidate has rarely put a foot wrong when it comes to Israel. As a senator, she proved a diligent and contentious friend of the Jewish state. She campaigned to bring Magen David Adom into the International Red Cross Committee and doggedly raised the issue of incitement in Palestinian schoolbooks. On a trip to Israel in 2005 she full-throatedly endorsed the building of the separation barrier, and a year later addressed a rally outside the UN supporting the Second Lebanon War. When she ran for the Democrat nomination in 2008, she won the backing of the overwhelming majority of Jewish voters.

Her Aipac address was interrupted by applause 55 times

It would, however, be wrong to characterise Mrs Clinton's stance on Israel as purely driven by electoral politics. She has spoken frequently of the "enduring emotional connection to the land and its people" sparked by a visit to Israel in 1981. Her interest in an early years programme she witnessed on the trip led her to try to introduce it back home in Arkansas.

Mrs Clinton's recognition of the perilous domestic politics surrounding Israel, plus the front-row seat she had of her husband's ultimately frustrating attempt to broker a deal between Ehud Barak and a recalcitrant Yasser Arafat during his final months in the Oval Office, shaped her time as Barack Obama's Secretary of State. As Michael Oren, Israel's former Ambassador to Israel, suggests in Alter Egos, Mark Landler's newly published book about Mrs Clinton's tenure in the State Department: "The sense was, she wanted to keep a distance from the whole thing."

Since leaving the department, Mrs Clinton has continued to burnish her Zionist credentials. At the height of the 2014 Gaza war she appeared on The Daily Show and tangled with host Jon Stewart, who had bitterly attacked Israel the previous evening. She offered sceptical backing for Obama's deal with Iran, pledging that she would "vigorously" enforce it to prevent the Islamic state attaining the bomb. As she launched her presidential campaign last May, she wrote a public letter to Haim Saban - the Israeli-American Hollywood billionaire who has donated $30 million (£21 million) to the Clintons' campaigns - attacking the BDS movement and lauding the "modern day miracle" that is the Jewish state. Her address to Aipac in March, critics charged, made her sound like Benjamin Netanyahu: her audience certainly approved – she was interrupted by applause 55 times.

Mrs Clinton's political opponents, however, hope that the release of reams of emails from her controversial private server provides them with ammunition to dent the former Secretary of State's pro-Israel shield. Some of the ideas sent to her appeared somewhat off-beat, but there is little indication that Mrs Clinton endorsed them.

In the wake of the Arab Spring, Anne-Marie Slaughter, the former State Department Director of Policy Planning, emailed Mrs Clinton arguing that the time was right for the US to recognise Palestine. Beyond her instruction to staff to "pls print", we know nothing of her reaction.

Potentially more troublesome is Mrs Clinton's close relationship with Sidney Blumenthal, a long-time adviser who served in her husband's White House. Critics have frequently attempted to draw a link between his son, the virulently anti-Israel campaigner and writer Max Blumenthal, and Mrs Clinton. To them, the revelation that Mr Blumenthal regularly forwarded links to his son's pieces to her provided the smoking gun they had long sought. Some of the links appeared to pique Mrs Clinton's interest. But it is also not hard to conclude that some of her responses to Mr Blumenthal - "Pls congratulate Max for another impressive piece" - may simply have been her way of humouring an obviously proud father.

What is clear, moreover, is that Mrs Clinton knew when to push back on Mr Blumenthal when he made substantive policy recommendations. In April 2010, for instance, he suggested "a note of scepticism" about Israeli intelligence claims that Syria had scud missiles it wished to transfer to Hezbollah. "Scepticism not in order," Mrs Clinton simply replied.

Mr Blumenthal's decades-long loyalty, strategic acumen and penchant for the political gossip which she so patently relishes, guarantees him a place in any future Clinton administration. However hard their enemies look, however, nothing in their frequent email exchanges suggests Mrs Clinton's support for Israel is anything other than the "unbreakable bond" she proclaims it to be.