In early 1988, Windham reunited with Luger and together they formed a tag team called The Twin Towers. On March 27, 1988 at "Clash of the Champions I" they won the NWA World Tag Team Championship from Arn Anderson and Tully Blanchard. A few weeks later, on April 20, in Jacksonville, Florida, a swerve took place where Windham betrayed Luger causing the team to lose the titles back to Blanchard and Anderson. Windham turned heel and joined Ric Flair's stable, the Four Horsemen (which also consisted of Anderson and Blanchard) and his heel turn was considered shocking at the time. In addition, he began using a black glove as well as the clawhold as his finisher, which was a signature move of his father Blackjack Mulligan. He went back to singles competition and defeated Nikita Koloff in a tournament final to win the vacant NWA United States Heavyweight Championship after then-champion Dusty Rhodes was suspended. Windham was a dominant US Champion, who reigned for nine months. He defended the title against the likes of Brad Armstrong, Dusty Rhodes, Sting and Bam Bam Bigelow before dropping it to Lex Luger at Chi-Town Rumble in February 1989. His contract expired in March 1989.