Wikipedia on the Israeli response to the 1972 Summer Olympic Games massacre in Munich

On 5 September [1972], Golda Meir, Prime Minister of Israel, appealed to other countries to "save our citizens and condemn the unspeakable criminal acts committed." She also stated, "if we [Israel] should give in, then no Israeli anywhere in the world shall feel that his life is safe ... it's blackmail of the worst kind."

Meir and the Israeli Defense Committee secretly authorized Mossad to track down and kill those allegedly responsible for the Munich massacre. The accusation that this was motivated by a desire for vengeance was disputed by Zvi Zamir, who described the mission as "putting an end to the type of terror that was perpetrated" in Europe. To this end Mossad set up a number of special teams to locate and kill these fedayeen, aided by the agency's stations in Europe.

In a February 2006 interview, Zamir answered direct questions:

Was there no element of vengeance in the decision to take action against the terrorists? 

No. We were not engaged in vengeance. We are accused of having been guided by a desire for vengeance. That is nonsense. What we did was to concretely prevent in the future. We acted against those who thought that they would continue to perpetrate acts of terror. I am not saying that those who were involved in Munich were not marked for death. They definitely deserved to die. But we were not dealing with the past; we concentrated on the future. 

Did you not receive a directive from Golda Meir along the lines of "take revenge on those responsible for Munich?"

Golda Meir abhorred the necessity that was imposed on us to carry out the operations. Golda never told me to 'take revenge on those who were responsible for Munich.' No one told me that.

The Israeli mission later became known as Operation Wrath of God or Mivtza Za'am Ha'El. [Simon] Reeve [, author of One Day in September] quotes General Aharon Yariv—who, he writes, was the general overseer of the operation—as stating that after Munich the Israeli government felt it had no alternative but to exact justice. 

We had no choice. We had to make them stop, and there was no other way ... we are not very proud about it. But it was a question of sheer necessity. We went back to the old biblical rule of an eye for an eye ... I approach these problems not from a moral point of view, but, hard as it may sound, from a cost-benefit point of view. If I'm very hard-headed, I can say, what is the political benefit in killing this person? Will it bring us nearer to peace? Will it bring us nearer to an understanding with the Palestinians or not? In most cases I don't think it will. But in the case of Black September we had no other choice and it worked. Is it morally acceptable? One can debate that question. Is it politically vital? It was. 

[...]

Simon Reeve writes that the Israeli operations continued for more than twenty years. He details the assassination in Paris in 1992 of Atef Bseiso, the PLO's head of intelligence, and says that an Israeli general confirmed there was a link back to Munich. Reeve also writes that while Israeli officials have stated Operation Wrath of God was intended to exact vengeance for the families of the athletes killed in Munich, "few relatives wanted such a violent reckoning with the Palestinians." Reeve states the families were instead desperate to know the truth of the events surrounding the Munich massacre. Reeve outlines what he sees as a lengthy cover-up by German authorities to hide the truth. After a lengthy court fight, in 2004 the families of the Munich victims reached a settlement of €3 million with the German government.

~ "Munich massacre," Wikipedia