In an opinion piece published recently in the New York Times with the headline of "A Preventable Massacre," Seth Anziska writes that in September 1982, West Beirut was practically devoid of Palestinian terrorists; thus, he continues, it was clear to all concerned that if the Christian Phalange forces were allowed into the city's western sector, they would carry out a massacre against the Palestinian civilians living there. He argues that there was no need at all for a military presence in the area, and charges that the very act of allowing the Lebanese militiamen in was, in fact, a massacre in the making.

These are grave accusations that have been published by a respectable newspaper – yet they are not the truth. The facts say otherwise; the findings of the Israeli state commission of enquiry paint a different picture; and two courts of law, in New York and in Israel, ruled differently too.

At the time, Israeli intelligence assessments spoke of 2,000-2,500 Palestinian terrorists still remaining in West Beirut, over and above the 9,000 who had already been deported a number of days earlier.

At a meeting in Lebanon on September 12, 1982, then Israeli defense minister Ariel Sharon and Lebanon’s newly elected president, Bashir Gemayel, discussed the need to ensure that the area was totally cleared of terrorists.

Their concern was that these terrorists would serve as the basis for the reestablishment of the Palestinian terror state within Lebanon – the same terror state that had just been dismantled. This Palestinian terror regime had been responsible for the shelling of northern Israel and for making the lives of the civilians there insufferable; it had been responsible for acts of terror against Jews in Israel and around the world; and it had all but eradicated the existence of Lebanon's sovereignty.

Israel and Lebanon's president-elect shared a common interest – to prevent the reemergence of the terror state. They agreed that Lebanese forces, which were more suited to the task than the Israel Defense Forces troops, would carry out the sweep of West Beirut; for one, the Lebanese forces spoke Arabic and could pick up on the different dialects.

Furthermore, pressure inside Israel called for Lebanese participation in the war against the terrorists too – after all, it was their capital; they wanted to unite it and maintain control over all of it; and they, too, should make an effort to this end.

How can it be argued that allowing the Phalange forces into West Beirut was an act of retribution for the assassination of Gemayel when the understanding to allow them in was made with Gemayel himself two days before his assassination?

Furthermore, the assassin wasn't even a Palestinian; he was Christian just like Gemayel, working in the service of the Syrians – a fact that was already well known at the time of the massacre. So why would the Christians want revenge against the Palestinians for an assassination the Palestinians had nothing to do with?

Contrary to the claims made in Anziska's opinion piece, the Israeli chief of staff did not foresee the acts of murder perpetrated by the Lebanese forces in Sabra and Shatila – and the same goes for the Mossad chief, the head of the IDF's Military Intelligence Directorate and all members of the Israeli government at the time.

None of them foresaw or warned of such an eventuality. "No intention existed on the part of any Israeli element to harm the non-combatant population in the camps," stipulate the conclusions of the "Report of the Commission of Inquiry into the events at the refugee camps in Beirut, 8 February 1983," set up in Israel to look into the events in Sabra and Shatila.

In February 1983, Time magazine published an article claiming that then-Israeli defense minister Sharon had encouraged the Christian Phalanges to take revenge for the assassination of Gemayel. Sharon sued the magazine for libel. In January 1985, a New York court ruled the article was both false and defamatory, finding that "certain Time employees had acted negligently and carelessly". Time paid compensation in Israel for the false publication.

So why then did the Christians massacre the Palestinians in September 1982? An answer to this questions is offered by Robert Hatem (code-named "Cobra"), who served as right-hand-man to Eli Hobeika, the commander of the Phalange forces that carried out the murders in Sabra and Shatila.

In his book, "From Israel to Damascus," published in 1999, and in an interview with the Maariv daily in August 3 2001, Hatem claims that the Israelis demanded the Phalange forces to operate as a respectable orderly army and that the IDF's officers were shocked and furious when they learned about the events.

Furthermore, Hatem claims that the commander of the Phalangists, Hobeika, was working in the service of the Syrians and that the massacre was carried out at their behest with the aim of tarnishing Israel's reputation worldwide. That may have been the reason; in any event, the moment Israel learned that the Lebanese forces were carrying out unspeakable acts, IDF troops stepped in to put an end to the killings and to remove the Phalangists from the area. To this end, IDF troops even opened fire on Christian forces who had worked in close cooperation with Israel for many years.

These are the facts.

It was sad and shocking – but that's Lebanon. It wasn't the first massacre in the country, and it wasn't the last either.

Massacres among the various sects in Lebanon were commonplace throughout the 20th century, and particularly after the outbreak of the country's civil war in 1975.

In December 1975, members of the Palestine Liberation Organization murdered dozens of Christians in Beirut; in January 1976, Christian forces slaughtered around 1,000 Palestinians in Beirut's Karantina district; two days later, Palestinians murdered hundreds of Christians in the town of Damour; in July of the same year, PLO forces murdered some 120 Christians in Chekka, in northern Lebanon; in August, Christian forces killed around 3,000 Palestinians in the Tel al-Zaatar refugee camp in northeast Beirut; in October 1976, Palestinian terrorists and locals Muslims murdered dozens of Christians in the village of Aishiya in southern Lebanon; in July 1980, the Phalangists murdered members of a rival Christian sect; in 1983, Syrian forces killed a large number of Palestinians in the refugee camps around Tripoli; and in 1985, Shia forces slaughtered Palestinians in Beirut – not to mention all the assassinations; for example, that in February 2005 of former Lebanese president Rafic Hariri, a crime to which Hezbollah and Syria adamantly deny any connection despite the findings of the special international court that investigated the killing. Hariri's assassination also claimed the lives of another 20 people.

That's Lebanon; and from that perspective, the acts of murder in Sabra and Shatila were not an anomaly in the bloody history of this deeply divided country.

In fact, when the Lebanese forces operated under the direction of the IDF during earlier incidents in the war in Lebanon, they operated as a professional and orderly military force and refrained from perpetrating mass killings. Such was the case during their operations in the Beirut suburb of Reihan, in the area of the science college, and in the Druze region of the Chouf Mountains. There and elsewhere, while operating under the direction of the IDF, there were no incidents of mass killings like took place in Sabra and Shatila.

Double standards ruled then just as they continue to rule today. No one appeared to take any interest in the countless number of victims of massacres that took place in Lebanon both before and after the mass killings in Sabra and Shatila – perhaps because there was no way of tying Israel to any of the incidents, albeit even indirectly.

The bottom line is that these were Christian Arabs who murdered Muslim Arabs – and the world reveled in the bloodshed and came down hard on Israel, the same world that failed to shed a single tear for the tens of thousands killed by Hafez Assad in the Syrian city of Hama in February 1982, and finds no tears today, too, for the tens of thousands of victims of Assad Jnr.

The world's conscience proved deeply sensitive when the victims offered a degree of political clout, clout in the form of propaganda ammunition against Israel. Yet, with nothing whatsoever to gain from the suffering of the victims, the very same conscience remained impressively unmoved, and continues to do so today, too.

Gilad Sharon is the youngest of former Israeli Prime Minister Ariel Sharon’s three sons and was a confidant to his father. Sharon holds a master’s degree in economics and writes a frequent column for a major Israeli newspaper. A major in the Israel Defense Force reserves, Sharon currently manages his family’s farm in Israel. His book about his father, "Sharon: The Life of a Leader" was published by HarperCollins on October 25, 2011.