On 5 May 1980 the sixth day of the siege dawned. Fatigue and tension had set in on both sides. The gunmen were frustrated because their demands had not been granted. After many threats they finally executed a hostage. The body of Abbas Lavasani was pushed out of the embassy at about 1900. This marked a crucial escalation of the siege. The decision was taken by Prime Minister Margaret Thatcher to send in the SAS. Operation Nimrod was launched.