The Ambassador

U.S. Ambassador to Israel Peter Hacker (Robert Mitchum) and head of security Frank Stevenson (Rock Hudson) are en route to a secret location in the Judean desert to meet with representatives of the PLO (Palestinian Liberation Organization). It is part of Hackerâs secret plan to have young Jews and Muslims begin a peaceful dialogue. An armed Israeli helicopter locates and disrupts the meeting by firing on it causing several deaths. Hacker and Stevenson survive and are apprehended by Israeli ground soldiers.
Alex Hacker (Ellen Burstyn), the ambassadorâs troubled and lonely wife is in Jerusalem where she is secretly meeting her lover. However, she is followed and their tryst is caught on videotape by an unknown entity.
Hacker and Stevenson are taken to the office of Israeli Defense Minister Eretz (Donald Pleasence) who confronts them for not informing him on the meeting and reiterates his opposition to Hackerâs peace efforts. Upon returning to the American embassy Stevenson makes contact to a secret superior where he also voices his concerns and wishes to see an end to Hackerâs assignment as ambassador.
At a diplomatic function later that night Alex is drunk and making a scene. She leaves early by taxi to meet with her lover once again. While calling him from a phone booth in front of his apartment an explosion goes off injuring her and killing several others. Hacker and Stevenson head back to the ambassadorâs residence, not knowing Alexâs whereabouts. Hacker is telephoned by an unknown man telling him to make contact at a movie theater, alone. After his arrival he enters the damaged building where the film of his wifeâs infidelity plays on a movie screen. Stevenson, who is not far behind, shares in the discovery.
Hacker is informed that his wife is safe and making a full recovery in hospital. He along with Stevenson visits her where she tells him that she wants to get out of Israel. Back in his office he is again contacted by the unknown man. Conditions are made that if one million dollars in hush money is not paid the film will be released and a private copy will be made available for the President of the United States. Hacker refuses. They also mention the name of Alexâs lover, prompting him to have Stevenson investigate further. Hacker later confronts his wife that night and tells her of the affair and blackmailing scheme.
Alex again visits her lover to find his true identity. He turns out to be Mustapha Hashimi (Fabio Testi), a wealthy business man and PLO member. Minister Eretz is informed of the situation and finds the film was made by Mossad agents to keep tabs on the Hacker's and its prints stolen under their noses. Stevenson makes headway finding the location where the film was developed and visits the print shop looking for answers. After being duped and knocked out he catches a woman from the shop and offers her protection. She then reveals the identity of the blackmailers.
Hashimi is also blackmailed for $500,000 and decides to pay. After learning of this Hacker sets up a meeting with Hashimi and sees an opportunity to use his influence within the PLO to have a peaceful meeting between Jewish and Muslim students to which he agrees. Stevenson interrogates the two blackmailers who reveal that Hacker is being pursued by a KGB assassin named Stone.
The Ambassador conducts the meeting with Israeli and Palestinian students at an ancient Roman ruin outside of Tel Aviv and it ends with progress between the two parties. However, Palestinian terrorists ambush the students causing a bloodbath and Hashimiâs assassination. Israeli authorities, Alex and Stevenson arrive to find Hacker alive and head back to the residence where Stone is waiting for him. Just as he is about to make a clean shot from his car Stevenson shoots Stone in the back of the head, leaving the ambassador unscathed. While sitting with his wife, Hacker tells her that he is thinking of resigning but she disagrees and favors him staying on. He later walks outside onto his front porch only to see a group of young Israeli students holding a peace rally bringing him to tears.

Question: Who is blackmailing Hacker?
Answer: An unknown man.