Along with a number of other Soviet chess champions, he signed a petition condemning the actions of the defector Viktor Korchnoi in 1976.
It was the continuation of a bitter feud between the two, dating back at least to their 1974 Candidates semifinal match in which Petrosian withdrew after five games while trailing 3½–1½ (+3−1=1).
His match with Korchnoi in 1977 saw the two former colleagues refuse to shake hands or speak to each other.
They even demanded separate eating and toilet facilities.
Petrosian went on to lose the match and was subsequently fired as editor of Russia's largest chess magazine, 64.
His detractors condemned his reluctance to attack and some put it down to a lack of courage.
At this point, however, Botvinnik spoke out on his behalf, stating that he only attacked when he felt secure and his greatest strength was in defence.

Some of his late successes included victories at Lone Pine 1976 and in the 1979 Paul Keres Memorial tournament in Tallinn (12/16 without a loss, ahead of Tal, Bronstein, and others).
He shared first place (with Portisch and Hübner) in the Rio de Janeiro Interzonal the same year, and won second place in Tilburg in 1981, half a point behind the winner Beliavsky.
It was here that he played his last famous victory, a miraculous escape against the young Garry Kasparov.
Along with a number of other Soviet chess champions, he signed a petition condemning the actions of the defector Viktor Korchnoi in 1976. It was the continuation of a bitter feud between the two, dating back at least to their 1974 Candidates semifinal match in which Petrosian withdrew after five games while trailing 3½–1½ (+3−1=1). His match with Korchnoi in 1977 saw the two former colleagues refuse to shake hands or speak to each other. They even demanded separate eating and toilet facilities. Petrosian went on to lose the match and was subsequently fired as editor of Russia's largest chess magazine, 64. His detractors condemned his reluctance to attack and some put it down to a lack of courage. At this point, however, Botvinnik spoke out on his behalf, stating that he only attacked when he felt secure and his greatest strength was in defence.
Some of his late successes included victories at Lone Pine 1976 and in the 1979 Paul Keres Memorial tournament in Tallinn (12/16 without a loss, ahead of Tal, Bronstein, and others). He shared first place (with Portisch and Hübner) in the Rio de Janeiro Interzonal the same year, and won second place in Tilburg in 1981, half a point behind the winner Beliavsky. It was here that he played his last famous victory, a miraculous escape against the young Garry Kasparov.
Tigran Petrosian