WASHINGTON — ABL Space Systems, a six-year-old launch startup, announced it is exiting the commercial launch market to focus on missile defense programs for the Pentagon. The move comes after a string of setbacks and mounting challenges in gaining traction against dominant players like SpaceX and Rocket Lab. “We are stepping away from the commercial launch market and focusing our efforts on missile defense,” ABL’s co-founder and president Dan Piemont said in a social media post Nov. 14. He cited diminishing opportunities in the launch industry and geopolitical tensions as…