At the same time, both the US and USSR were in the midst of introducing their first truly mass-produced ICBMs, and their numbers were clearly going to grow dramatically during the early 1960s. Zeus, like Hercules and Ajax before it, used mechanically directed radar dishes that could track only one target and one interceptor at a time. It was planned that Zeus bases would actually consist of several launcher sites connected to a central control, but, even in this case, the site might be able to guide four to six missiles simultaneously. As the ICBM fleet numbered hundreds even before Zeus could become operational, it would be simple to overcome the defense by directing sufficient warheads over it to overwhelm its ability to guide interceptions rapidly enough.