Operation Regenbogen had been planned before the December battle, but changes to Allied shipping disrupted the opportunity to use it. Operation Torch suspended some Arctic convoys. Operation FB then sent ships independently, producing targets that did not justify deploying the full German surface force. British submarines remained a threat outside the German bases, so a sortie carried risks even before the Germans reached a convoy.
Notable Point · 2:34:36-2:35:21
Why Torch and independent sailings delayed Regenbogen
Suspended convoys and scattered independent sailings deprived the German surface force of a target worth the risk of deploying.