WASHINGTON (Reuters) -The Trump administration is expanding its search for partners to build the Golden Dome missile defense system, courting Amazon.com's Project Kuiper and big defense contractors as tensions with Elon Musk threaten SpaceX's dominance in the program, according to three sources familiar with the matter. The shift marks a strategic pivot away from reliance on Musk's SpaceX, whose Starlink and Starshield satellite networks have become central to U.S. military communications. It comes amid a deteriorating relationship between Trump and Musk, which culminated in a public falling-out on June 5.