The Missile Defense Agency is seeking industry proposals for a new class of low-cost interceptors to blunt the threat of massed missile attacks in a new project that aims to develop modular weapons that cost less than $750,000 apiece and can be produced on a compressed schedule to counter ballistic, cruise and hypersonic threats. On Aug. 27, MDA asked industry for white papers on “innovative approaches to rapidly demonstrate very low cost . . . kinetic defense solutions” that could...