Due to the rematch clause of the 1985 match, Garry Kasparov was forced to defend his title against Anatoly Karpov in 1986. However, no sooner did the 1985 match end, the details of this rematch were already being hotly contested.
FIDE president Campomanes declared that the rematch would take place in February of 1986, only three months after the previous match, instead of waiting the customary 12 months. On December 30, 1985, Campomanes gave an interview to the Associated Press in Geneva, stating that Kasparov would have until midnight January 7, 1986 to accept these conditions, and if he did not, Karpov would be declared world champion. Kasparov, however, stood firm to his convictions, announcing that he would not participate in the return match so soon after the first match had ended.
To break the deadlock, the Soviet chess federation met on January 21 and decided that the match would take place in July or August. Kasparov and Karpov signed an agreement on the following day without consulting FIDE:
A week later both players then flew together to FIDE headquarters in Lucerne to meet Campomanes, to present their plans to FIDE, and to finish the arrangements. On 29 January, Campomanes gave a press conference, announcing the terms of the match.
The match was agreed to begin in July, played in both London and Leningrad, making this the first world championship between Soviet players to be conducted outside of the USSR. The British used the occasion to celebrate the 100th anniversary of the first world chess championship, Zukertort vs Steinitz, 1886.
On July 28, the match began. GM Lothar Schmid was the chief match arbiter. GM Ray Keene was the chief match organizer for the London leg. British Prime Minister Margaret Thatcher conducted the color selection.
On October 8, 1986, Kasparov retained the World Championship title.