We have satellites that we use to detect launches, and which can warn the tracking stations in Alaska and California of the threat.
You are, once again, correct in your assessment of the satellite threat detection network. But they don't qualify as fire-control radars. The ones in eastern Europe will. That's why we need them there.
They also serve as a threat deterrent/tripwire against Russia. Putin knows that once those radars are online, he cannot act against them without inviting an American preemptive nuclear launch. The only reason he would strike at them would be to clear the way for his own first strike. The second he takes them out, we launch before he does. That's why he's doing everything he can to keep them from being installed. And our girlfriend President is being very accommodating.